That idea crossed my mind today but since I'm getting some Masstick tomorrow, I'm going to try sticking that to rocks first...I'm really hoping they'll like that stuff but either way I'll later try with cut up pieces of clam because I want to feed them a natural diet if possible.If that don't work try this,since they picking at rocks looking for food take the calms out of shell slice them up small bites ,turn off pumps for a few hrs and put that food on rocks where they was picking at.Only try 1 shell at a time also ,find some small mysis shrimp also and put on rocks when pumps are off ,since they was picking at rocks they do eat just have to find what they eat