whats this, coral bug or coral guts?

[ocyoo]

I have these things on my mushroom and they are not moving, they look like intestines or some kind of worm! ID plz.

 

[spanko]

Look like spirorbid worms, but I have never seen them growing on a mushroom before. Must be something else. Let's see what others say.

 

[renogaw]

its from a stressed out mushroom, those are their defense mechanisms

 

[snakeblitz33]

looks like a stressed mushroom, something picking at it or the water quality is bad. That white stringy stuff is somewhat toxic to fish and/or anything eating it. No worries.

 

[ophiura]

I agree, they are defensive structures (acontia) from the mushroom.

 

[paintballer768]

Judging by how clean the rock is, was it recently fragged? If so, that would be an expected mechanism