Question about this item

[Greendragon245]

Sorry I don't remember the name of the item its a blue tinted butterfly that shows me the locations of secret rooms and tinted rocks and maybe trapdoors.

So my question is that I was in a room with webs in the corners it flew to 1 and stayed their like its important blew it up nothing happened and now its roosting above some water in a room is their anything actually their??

[dribson]

The item is called YO LISTEN[bindingofisaacrebirth.gamepedia.com]
It hovers over secret rooms and trap doors. It's probably seeing a trap door in the space, but since there's no rock there, it can't be accessed.

[Greendragon245]

so is it a bug or what? no reason really for the butterfly to hover over a place I can't access

[dribson]

It's 'working as intended', in that it's telling you about a crawl space. There just happens to not be a rock to destroy to access that crawl space.
I'd just ignore for the room if that's the case.

[Greendragon245]

ok thanks

[LSDBunny]

I think it's possible to reroll cobwebs with the D12, so that the crawl space should become accessable.