identify something a snail

[dfos00]

I have a trochus snail with lots of stuff on its shell.  I know there is algae and some other things but what is this in the red circle.  It appears to have 2 round vents that I have seen contract.  Please let me know what it is and if it is harmful.  Thanks

[yagerboy]

Sea squirt?

[DaJMasta]

Yeah, some kind of tunicate.

[DFR]

It looks like a sponge to me.  My gues would be that what ever it is, it isn’t harmful.  Maybe if you get a pic from the side we may be able to better identify.