What are these?

[horseplay]

These are on my overflow box. Some have hatched.

I suspect these are the babies. Like a snail but without the spirul shell, just a clam shell.

 

[jgraz]

The eggs look like nerite snail eggs.

The baby you have there is a stomatella.

 

[MatteZ]

Yup what John said. The eggs wont hatch. I think they need brackish water.