What's this little purple creature?

[BitFix]

Today while doing maintenance on my reef tank I found what I thought was a small purple cyano patch, but at closer inspection it seemed to have a mouth and looked more like a small purple mushroom coral. It does apear to have a foot of some kind, but when I touched it it didn't seems to react in any way. It's a little while since I've added anything wet to my tank, so I guess it was there for some time.

Sorry for potato quality photo

 

[DSC reef]

Looks like a hitchhiker discoma

 

[BitFix]

Looks like a hitchhiker discoma

That was my guess, thank you! Do you know if this kind of mushroom will spread too quickly? Like GSP or Xenia? If so I'll need to give it its own island

 

[DSC reef]

They can grow quickly but not as fast as the other corals, might be a good idea to isolate still.

 

[BitFix]

They can grow quickly but not as fast as the other corals, might be a good idea to isolate still.

Are they able to release free-floaters like xenia?

 

[DSC reef]

They can detach themselves if unhappy like an anemone

 

[BitFix]

They can detach themselves if unhappy like an anemone

Thanks!