Help with an ID please

[Aliciasfish]

This thing hasn't moved. I've combed the web with no id possibility except either plate algae or a flower anemone. I have no idea really. New tank, about three months old, 26 gallon. Combination of LEDs and white/blue T5HO lighting. No filter, No Skimmer. One jet, debating adding the second one I purchased.
It's been an adventure..

2 Yellows belly damsels
2 clown fish
Ricordia Mushroom Coral
1 cleaner shrimp
3 peppermint shrimp
CUC from Reefcleaners (lots of snails!)

 

[Sniperhank]

Hard to see. Can you get a picture with the whites on and no flash?

 

[Aliciasfish]

Yes, I will when I get back home. ?

 

[Aliciasfish]

Here is a shot under whites no flash

 

[Aliciasfish]

Close as I could get it.

 

[PrettyFish]

I wonder if it's a sponge? Just a guess

 

[Aliciasfish]

Could be a sponge. I hope it's harmless.

 

[Aliciasfish]

Overrun with Dwarf Ceriths snails.. These things reproduce so fast. Think my LFS will buy some off of me?