identify please...

[mzeinstr]

this is growing on a zoo rock that i purchased about 2 months ago.
the base is black, with a kind of white polyp. it's about 1/2 to 3/4 of an inch now and growing. it is alive as when i close the cabinet door it shrinks.
anyone?

 

[mzeinstr]

 

[sammiefish]

what exactly is the question?

 

[mzeinstr]

see the subject? identify please.....
photo in next frame.
thanx.Z

 

[sammiefish]

OH...Sorry!!! I see that thing now...
All I saw the first time was zoos growing on the zoo rock