Unicorn asterina?? What is this creature?

[damselindistress]

I have a 60g AIO that's been running about 3.5 months, I upgraded from an Evo 13 that was roughly a year old, so it didn't start completely "fresh".

This week I was cleaning out the back chambers and noticed both rear chambers are heavily populated with these critters. At first I thought I'd overfed on mysid but on closer inspection I see that they are something else entirely. Anybody have any idea what they are??

 

[James M]

They look like sponges but hard to tell from the pic

 

[KJ]

^^^Sponge harmless filter feeder

 

[damselindistress]

^^^Sponge harmless filter feeder

Are they okay to leave or do I need to do away with them? Thanks!

 

[Ranjib]

They are okay