What is this walnut looking thing? (pics)

[ironmanxl1]

There is this walnut shaped thing on one of my rocks.
At first I thought it was part of the rock until it pooped a long string.
And it shrunk up a little when I put some light on with the camera. It's brown , has a red hole on one end and is a little over an inch long.
I also saw a tiny brown crab crawling around. I wouldve taken a picture but he was too quick. are there any good brown crabs? Or are all crabs bad?

 

[Fluff]

I see two openings. Looks like a tunicate.

 

[Brad]

I agree.

 

[ironmanxl1]

Thanks for the ID. After doing some research on tunicates i found that i have ALOT of them. lucky me I guess.

 

[Oceanicsublimat]

well.. not really lucky.. they don't last long.. hard to feed..

 

[ironmanxl1]

oh . that stinks. some seem to be growing well too. time will tell