ID this hitchhiker please.

[planemechfj]

The white stringy looking thing with the red dots? The white stringy parts with red dots are similar to tentacles that recoil into a pouch or mouth. there are at least 6 tentacles and it was feeding by extending them then recoiling after catching something.

 

[bang guy]

I will guess that there are actually ten tentacles. I believe you have a sessile Sea Cucumber. They are harmless filter feeders and rarely ever leave their hole in the rock.

 

[planemechfj]

after looking at some pictures, I think you called it. Thanks for the ID.

 

[bang guy]

I think they're pretty cool critters. A squirt of oyster eggs once in a while will keep them healthy.