My little serpent star comes flying out from under his rock when I feed the tank a half capful of mirco-vert food. I use the Kent micro-vert food for filter feeders and inverts (Careful, it looks similar to the bottle that Kent sells its strontium in, dont want to be dosing are little non coral friends with SR..Kinda like mixin up the skinny n sweet with rat poison..ok Im old now.) . They completely dig it. Not a great diet by itself, but if you truly have no live rock, little star-dude is gonna have a tough time foraging.
To fail to plan is to plan to fail.