Something growing on frogspawn

[nibra]

can anyone ID this? All lights have been out for a good while so everything is closed up and I spotted this while checking how everything is doing. Hard to get a pic as my tank is in an odd spot but it looks like a clam of some sort growing on the skelton of the frogspawn.

 

[Tahoe61]

Looks like a bivalve. Does it open and close?

 

[Fish Styx]

Looks like a bivalve. Does it open and close?

+1