mine came with my live rock

IMHO pom poms are more decorative than useful. (darn cute though)

I know someone who had their tank nuked due to a cuke dying, so due to that I would not recommend them. The bristleworms and possibly microstars (micro brittle stars) that come in off most live rock are very good detrivores. I

Golds sells conches (I think called fighting conches, also called orange lipped though I see no orange) and I bought one from there. It loves to clunk about in the sand and eat stuff with its "trunk".

I like the tri-color hermit crabs for hc's. I found most other kinds ate my snails and each other.

If you just want to stir your sand bed up and have room for the bio load of a fish, a goby is nice. Their are several gobies that sift sand. The ones in my tank are Signal and "Dragon" (can't remember the scientific names).

Most people recommend against getting a "sand dollar" as they often have bad survival rates in the aquarium..same goes for sand sifting starfish.

Another cleaner upper I really like is the money cowrie. It is small, Golds sells them as well.