Who eats valonia?

[Delphinus]

I forget, who eats valonia (bubble algae)? Is it emerald crabs or sally lightfoots?

I seem to think that it's emerald crabs that eat valonia. Can somebody confirm this?

I have a general mistrust of anything with claws. Will an emerald crab be safe in a reef, really? Really really? What will they eat once the valonia is gone? Will they leave my baby clams alone?

Thanks in advance!