ID on what's growing on rock?

[NYLouie]

Can anyone ID what these things are? Its in my 10gal nano, I have live rock and dead rock. They are growing more on my dead rock but a couple has pop up on my live rock. I do notice that some fall off because they get stuck on my powerhead. The tank is 3 months old. It is stocked with:

Black Ice Clown
Picasso Clown
2 x Emerald Crabs (relocated from my 36gal after seeing them nipping at my corals)
Hermits Crabs
Turbo Snails
Bubble Bee Snails
Nassarius Snails
2 x Anemones

Just wondering if this is something I should be worried about. Here are pictures:









Thanks

 

[Greagzter]

Its a pineapple sponge

 

[fishman1069]

+1

 

[NYLouie]

thanks for the help. really appreciate it.

 

[PeteTheGreek89]

Its a pineapple sponge

+2

i have hundreds.