I had tons of tiny trochus snails born in my 40B. They never seemed to really grow and were all the same size for a long time. Since my upgrade to a 180 i have seen a half dozen that were 5 to 6 times bigger than those little ones but smaller than any i have bought. They are the only snail i have that legit produce more workers. They also flip themselves back over. Probably one of the best purchasable cleanup crew members.
I have a few blue leg hermits, a tiger conch, some Nassarius snail, one lasting astrea, 4 pithos crabs, sand shifting starfish (2 inch sand bed 60x30 footprint).
I loved my pincushion urchin but he grew fast and was always moving frags. Once all my frags are locked down permanently i will have another.
Never had issues with an emerald crab and i have had at least one giant.
I probably need twice as many snails as i currently have.