Serpents/brittles are the best. However they really arenít active until nighttime.
I just recently got a marbled fromia starfish who is very cool but have a horrendous captivity survival rate. Iíve had it about a month and is doing great but my tank is well established and these stars donít clean the sand.
20 Gallon SPS reef
29 Gallon FW "fat catfish" tank
20 Gallon Long Dart Frogs "Zig" and "Zag"