What are these???

[sh8wn9]

So, the tanks been up for like a year and a half now...and Ive always wondered what these are. They are very slow growing, and Ive always thought that they were polys which were spreading, but they never grew that "flower" head. They are dark purple and skinny with a few holes in them. Are they sponges??? Anybody know???

 

[SecretAgent]

its sponge....means your tank is in very good condition and ageing well....I have those all in my tanks...some black, some white and some gray

 

[sh8wn9]

cool...great thanks for the id