New baby toadstool leather?

[Miami Reef]

This was not there until very recently. What is this?

 

[nfrench2100]

Sponge maybe?? Kind of hard to tell from the pic. Got a close up?

 

[DSC reef]

Hard to tell but I'm leaning towards a baby toadstool

 

[Miami Reef]

It got bigger.

 

[Rakie]

it looks like there's a trail of them to the right of it. Looks like some kind of polyp. Cloves maybe? hard to tell, but doesn't look anything like a toadstool. Looks like a pest to me.