What is this critter

[jejeclav]

This morning I found this critter on the glass of the tank. It does not move and it is roughly 2 inches diameter. I already noticed it a couple of days ago on another place. At that time, I thought it was a small trash floating around... it seemed to have grown significantly.
Any help would be appreciated

 

[mogurnda]

Looks kinda like a string of cerith snail eggs.

 

[Oliver]

I agree, doesn't look like an animal as such, my snail eggs look a bit like that too

 

[jejeclav]

thanks... there are indeed 12 cerith snails, 12 nassarius snails and 12 astrea snails in the tank. Do I have to do something special when the snails "grow"?
Do they have predators (I only have 2 ocellaris clown fishes and 3 blue chromis). Could crabs be predators?