[DAHansen]

I've seen micro-brittle stars available on eBay and around various places.

I've never seen SMALL clams and muscles other than what comes on live rock on occasion.

I would wait at least a few months before adding creatures as sensitive as stars and clams - they need a very stable environment.

Also, if you get some good live rock, you will end up with a LOT of diversity - I wish I had originally taken longer to add livestock in order to let my liverock more fully "develop."