Can someone I.D this?

[Brianscherer]

I found this guy growing on my rock about a month ago but it was very tiny and appeared not to like high light so I moved the rock and since it's grown large enough to get a picture.

 

[Rtaylor]

Pseudocorynactis caribbeorum, aka, Ball anemone. Which is actually a mushroom not an anemone.

 

[WheatToast]

Pseudocorynactis caribbeorum, aka, Ball anemone. Which is actually a mushroom not an anemone.

+1
These are benign, hitchhiking corals that are not as invasive as Aiptasia.