Saw something weird on my seeding rock

[Cuong]

Decided to seed my new tank at home with a piece of live rock from my 3 year old display at work. Saw this on there. Never seen it before in the display tank until now. Curious as to what it is. It has a mouth and tenacles like a scoly, in facts its 8” from a scoly. Not really sure what it is. One of them had a huge piece of chum in its mouth. Any takers on which hitchhiker this is.

 

[Crabs McJones]

Looks like ball anemones. Generally harmless if kept in check :)