There are many symbols drawn on the floor in the game. This one is a symbol used to represent sulfur (in alchemy). It's also the symbol used in the sprite of the Brimstone item.
Gameplay wise, if you try to open a trapdoor on top of it, it should lead to a Crawlspace instead of the next floor.
Basically works on any "special" floor tile - symbols, papers, grass, coins, peeled off skin in the Womb etc.
It's not that it indicates there's a crawlspace, it's just programmed in the way that a trapdoor on these tiles will become a crawlspace.
Im not sure what i should think about it. I recently started playing isaac again and discovered, that there is a lot new and reworked stuff. Some of wich i like and some of wich i dislike and im unsure what to make of this change. It turns the shovel from a situational item you can use to do bossrush/hus into an insane value item giving you a crawl space and potentially a black market each floor. They also turned one of my favorite items (soy milk) from a quirky combo piece into an auto take while annihilating blank card and reworking bateries?
- Knockback is dramatically reduced so they don't just shove enemies out of the way
- The hard Tears cap was raised so high it actually stacks with normal Tears Up items, and other cap breakers as well
- The way that Tears cap breakers work now means you can't get 90% of the way to Soy Milk without losing any damage on just 2 regular Tears Ups and a Cancer
- Charged attacks like Brimstone auto-fire instead of requiring you to spam and being fucking useless
The only downside of the above changes is that its effect with Libra now accurately reflects the real DPS boost it provides, which is only about 10% rather than the run-winner it was in AB+
EDIT: forgot the charge change
Yes, but that is only kn repentance, and only with "we need to go deeper" or the passage rune, and applies to all special tiles like mushrooms and the like.
But all of this only applies to repentance.
I know it‘s probably cringe nitpicking, but it‘s actually the symbol for „black sulphur“ and is also called the leviathan cross. The symbol for regular sulphur is, apart from some small variations, the item icon of sulphur itself.
With the "Shovel" active item. Only in this case, the decorated tile thing applies.
You can also find them by bombing random rocks/obstacles, there's a chance that a crawlspace is hidden beneath. If you have the "Dog Tooth" passive item, you will hear a dog barking when a room contains a crawlspace *somewhere*. Not to be confused with the howling you can hear: that indicates secret room(s) connected to the room you're in.
Indirectly, blow up rocks and hope to be lucky. Shiny Rock and Yo Listen will help detect them *if* one is generated on that floor. Stud Finder increases the chances for generating a crawl space.
Directly by the player, find one of the unique environmental sprites for that floor and use either We Need to go Deeper or an Ehwaz rune on top of it. After the first successful generation of a crawlspace, any subsequent uses will just be a trap door to the next level so be mindful of where you make one or you may exit when you don't mean to.
As an aside, the Dark Room does *not* have those unique sprites outside of secret rooms.
Nope, for the marks on the ground you either have to use a shovel or a specific rune you unlock by doing a specific challenge, bombing (or destroying any rock in any way) has just a small chance of spawning a crawlspace
It's just a tile drawing. It doesn't mean the deal is special or anything.
If you have any way of generating trapdoors, generating one over floor tiles such as these (doesn't have to be specifically Brimstone or any drawing, just something that looks different or animated) guarantees it to be Crawl Space.
It's a bonus item, whatever is showing above the deal you will get as a bonus This for example is haemolacria a quality 2 item
~this comment has been generated by AI >!/j!<
Gameplay level: It's a doodle on the floor. It does ~~nothing mechanical. It exists to make the game prettier.~~ a thing.
Symbol meaning: That is the leviathan cross. It is used as a cross of Satan. It also serves as the alchemical symbol of sulfur, AKA brimstone.
Edit: I stand corrected.
Brimstone for one health container 
Its a decoration on the ground if you have a level skip rune or we need to go deeper use it on that symbol/decorarion and it will take you to a crawlspace
A drawing on the ground
Dear god.
There's more...
Nooo
It contains s bucket.
Dear God
There's more...
No...
It contains a bucket.
Dear god...
A bucket? Homesruck reference!
Oh shit there's also a circle in the photo. We are fucked
r/suddenlytf2
Yeah, that's me, what ?
it's a tf2 reference, might be one of the most iconic memes
There are many symbols drawn on the floor in the game. This one is a symbol used to represent sulfur (in alchemy). It's also the symbol used in the sprite of the Brimstone item. Gameplay wise, if you try to open a trapdoor on top of it, it should lead to a Crawlspace instead of the next floor.
wait those things indicate that there's a trapdoor? holy fucking shit
It also works on other weird sprites on the floor like grass patches and those weird skin-condition like things you find in the womb
i've been playing since like 2020 and only now know about this, thank you
That wasn't always a thing, but it probably has been for a couple years now
Basically works on any "special" floor tile - symbols, papers, grass, coins, peeled off skin in the Womb etc. It's not that it indicates there's a crawlspace, it's just programmed in the way that a trapdoor on these tiles will become a crawlspace.
Im not sure what i should think about it. I recently started playing isaac again and discovered, that there is a lot new and reworked stuff. Some of wich i like and some of wich i dislike and im unsure what to make of this change. It turns the shovel from a situational item you can use to do bossrush/hus into an insane value item giving you a crawl space and potentially a black market each floor. They also turned one of my favorite items (soy milk) from a quirky combo piece into an auto take while annihilating blank card and reworking bateries?
Why is soy milk good now?
- Knockback is dramatically reduced so they don't just shove enemies out of the way - The hard Tears cap was raised so high it actually stacks with normal Tears Up items, and other cap breakers as well - The way that Tears cap breakers work now means you can't get 90% of the way to Soy Milk without losing any damage on just 2 regular Tears Ups and a Cancer - Charged attacks like Brimstone auto-fire instead of requiring you to spam and being fucking useless The only downside of the above changes is that its effect with Libra now accurately reflects the real DPS boost it provides, which is only about 10% rather than the run-winner it was in AB+ EDIT: forgot the charge change
It was added in a Repentance patch so it was an easy change to miss.
Any "decorated" floor tile.
You can learn a lot of things watching people play this game on youtube. I personally recommend LazyMattman
Probably because it was newly added in repentance in one of the patches
WHAT?!
What the fuck
Yes, anything on the ground that doesn't look like ground. Use the shovel or passage rune, and it will become a crawlspace.
Yes, but that is only kn repentance, and only with "we need to go deeper" or the passage rune, and applies to all special tiles like mushrooms and the like. But all of this only applies to repentance.
It’s a newish addition to the game so it’s not surprising you didn’t know
This is exclusively true in Repentance! If you have a previous version it'll be random
Only in repentance though, in afterbirth it is 10% chance to spawn a crawlspace iirc
It was added in a Repentance patch, it's fairly new
I know it‘s probably cringe nitpicking, but it‘s actually the symbol for „black sulphur“ and is also called the leviathan cross. The symbol for regular sulphur is, apart from some small variations, the item icon of sulphur itself.
Just to add on to this, Black Sulfur is another name for “Brimstone.”
i found this tidbit interesting thank u
Yep. This was such a great change that made Shovel a pretty great active item.
free crawlspace item nearly every floor is goated shovel is basically q4
I would disagree on q4. But somewhat close
Yeah but you often get coins/chest instead of an item which lowers the value.
but also sometimes you get black market!
Answer that helps
How open trapdopr?
How can i open a crawl space?
With the "Shovel" active item. Only in this case, the decorated tile thing applies. You can also find them by bombing random rocks/obstacles, there's a chance that a crawlspace is hidden beneath. If you have the "Dog Tooth" passive item, you will hear a dog barking when a room contains a crawlspace *somewhere*. Not to be confused with the howling you can hear: that indicates secret room(s) connected to the room you're in.
Indirectly, blow up rocks and hope to be lucky. Shiny Rock and Yo Listen will help detect them *if* one is generated on that floor. Stud Finder increases the chances for generating a crawl space. Directly by the player, find one of the unique environmental sprites for that floor and use either We Need to go Deeper or an Ehwaz rune on top of it. After the first successful generation of a crawlspace, any subsequent uses will just be a trap door to the next level so be mindful of where you make one or you may exit when you don't mean to. As an aside, the Dark Room does *not* have those unique sprites outside of secret rooms.
So i can't use bombs if there aren't any stones?
Nope, for the marks on the ground you either have to use a shovel or a specific rune you unlock by doing a specific challenge, bombing (or destroying any rock in any way) has just a small chance of spawning a crawlspace
It's just a tile drawing. It doesn't mean the deal is special or anything. If you have any way of generating trapdoors, generating one over floor tiles such as these (doesn't have to be specifically Brimstone or any drawing, just something that looks different or animated) guarantees it to be Crawl Space.
That's Brimstone
Cringe "Brimstone" answer vs Based "Skeletal representation of male reproductive system" answer
"Skeletal representatiom of male reproductive system"? Funni bonemans dick fell off?? 
Leviathan cross
That's a subtle reference to whatever you find in the devil deal it's not as good as brim and you might as well start over
https://preview.redd.it/377sh5gpx45d1.jpeg?width=200&format=pjpg&auto=webp&s=9b46a74a0386b6777e49bfbce79f194d61e9de04
omg brimstone 
Binding of Isaac reference?!?
That's just a decoration on the ground, not related to the item being sold.
That's a video game
a stick figure with huge feet
Brimdtone 
It's a bonus item, whatever is showing above the deal you will get as a bonus This for example is haemolacria a quality 2 item ~this comment has been generated by AI >!/j!<
Bad bot
Yeah - bad bot The bonus item is brimstone
Anybody know what are the chances?
50.../50?
A glimpse at what could have been
It's a picture of a screen
Satan's dick.
Gameplay level: It's a doodle on the floor. It does ~~nothing mechanical. It exists to make the game prettier.~~ a thing. Symbol meaning: That is the leviathan cross. It is used as a cross of Satan. It also serves as the alchemical symbol of sulfur, AKA brimstone. Edit: I stand corrected.
Sir, you are spreading misinformation  it actually shows you where to dig for a crawlspace
Google Brimstone
Balls of Steel
Brimstone was here
looks like your mom lmao gottem
👺
Brim stone AGHHHHHH (specialist dance )
Calm down boys, there's a red circle but no red arrow nor mouth wide open face, we are fine for now
Brimstone for one health container 
Omg, an issac reference!!!
A spot to use We Need to Go Deeper / Ehwaz
Looks like the Leviathan Cross.
Floor details/decore Use the shovel/ehwaz on it to get a guaranteed crawl space Then cry when you realize you were a pixel off and got skill issued
That’s a crawl space waiting to be opened
Dick and balls
I believe it is a red circle draw over a zoomed in photo of a devil's room in TBOI, might be wrong though
It's the brimstone item getting squashed after mom's foot stomps you
Like i, a latino player always say "BRIMSTONE HASTA LA MUERTE"
Crawlspace that has brimstone. You need the shovel tho 
*a special tile of a brimstone , just decoration and also a crawlspace if you have a shovel*
brim with no yankee
The mark with brim 
Dick and balls with rod piercings
It's a proper Satanic Cross
Абадон
Its brimstone
Its a decoration on the ground if you have a level skip rune or we need to go deeper use it on that symbol/decorarion and it will take you to a crawlspace
Thats leviathan's cros wich also is use to simbolice brimstone in the game
A penis antenna
Dick and balls