y looking symbol on the floor?

[John The-ONE]

I encountered this thing in the sewers. It moves slowly up and down and is yellowish/brown normally but when I do jump and the move that hits the ground, it glows red but doesn't seem to do much other than that.

Anybody know what this is for? I took screenshot of it but I don't know how to embed it in the forum.

[Rick]

It shows breakable floors. There's a new rune you need to get to be able to break them.

[Moonbane]

Said rune is in the Ossuary