The Fire Shrimp is gorgeous -- if you ever get to see him.   The one I had spent 95% of the day hidden inside the rockwork.   It was a giant waste of money.

I leave chunks of frozen shrimp buried in the sand bed for my sand sifting starfish.  He will find them pretty quick.

I've noticed that crabs do better in community tanks, when they have they're own feeding Schedule

Pin cushion sea urchins are cool but they will absolutely demolish any expensive pretty macro algae you have in your tank. They also will eat all the beneficial coralline algae on your rockwork.

It was nice to see as a new reeder that I have made good choices in my new tank. Thanks for making me more relaxed !

I have a fire shrimp, they do the same thing lol. When he was small he was timid but as he grew he would come out more during feeding and take food from my torches. It’s not a big deal though, I just feed him first then the corals.

My red mithrax demolished my bubble algae, but then ended up picking at my rock flower anemones and some zoas. Had to buy crab pellets to feed separately because I'm almost 100% positive that it's also eating my aptasia.

I second the emerald crab.  Mine was doing his duty and helping with a hair algae problem.  Unfortunately I caught him multiple times trying to eat my duncan, and have seen him try to kill and eat nassarius snails more than once as they emerge from the sand.  He also ate any macro algae I tried adding to the tank and bullies my blue-leg hermits.

I moved my duncan to another reef tank and added a few Mexican turbos, which demolished the hair algae in a few days.  I like my emerald crab but would not get another one.

I had a camel shrimp in my reef tank, but it was picking at my soft corals (clove polyps, zoas, etc.), so I removed it.

Great information, especially helpfull for beginners. Peppermint shrimp are always a solid add. Crabs are always risky. Unpredictable some will eat corals.

I never seen my arrow crab picking up the bristle worms...and I never seen my emerald picking up the bubble algae...
The sand-shifting starfish is difficult to keep. Mine always start to melt after a few weeks time.

I can’t seemed to keep Emerald crabs for more than a couple of months.
I’ve seen other on blogs say the same.

THANK YOU FOR TEACHING ME

Great list of critters!  My two regrets were the Urchin and a bat crazy pistol shrimp!

My peppermint shrimp ate a very expensive Hammer Coral as soon as I put it in the tank wasn't happy about that also ate some Yuma mushrooms

arrow crabs are the only inverts my moray eels have killed. Didn’t even eat it, just killed one because it touched them

I've actually been thinking about getting one of those sea hares since my pin cushion, pencil, and long spine urchin are a bunch of freeloaders and don't do anything to my hair algae. I honestly don't know what they're eating cuz they're sure not eating the algae that's everywhere in abundance. It's either that or getting a small army of tuxedo urchins and hoping for the best.

My peppermint shrimp started going after my zoanthids.

I had lots of emeralds during the years and I was generally very happy with them. They stayed small, peaceful, model citizens with tiny claws and since then never had any algae problem. I always deliberately chose female ones as generally they are more reef safe according to the forums.
But when my new tank had a crazy macro algae explosion, I added two, a green and a red one. Both beautiful and very diligent removing the algae, cleaned it up in a month. But for some reason they both grew gigantic claws, enormous, never seen such thing. They didn't seem to bother anything, didn't lost any fish or inverts to them and they were really happy grazing algae, but sometimes they did wave their claws at some fishes, probably when they felt threatened. One time the red one even grabbed a butterfly fish and immediately started eating it. The fish was very weak because of the shipping stress, probably even half dead by that time, but I don't know if the crab just smelt dead fish opportunity or it would have grabbed it even if it was not on its last legs, anyway, I lost all my trust in them, started to imagine how they could catch my sleeping nano fish if hungry, so both of them went to the macro algae reactor. Hope they have a good time in there with the never ending buffet.

I have had a sand-sifting starfish in my 26 gallon tank for 1 year. I recently fount it lost the tip of his leg(not the whole leg), not sure if it was because of lack of nutrition in the sand.