The Emerald Crab, Mithrax sculptus, are one of the most popular marine crab species for the home aquarium. They thrive in tanks with plenty of live rock and a sandy substrate as the like to graze searching for algae. As voracious algae-eaters, they can be incredibly beneficial members of a cleanup crew. If there is not enough algae or seaweed, they can be supplementally fed with prepared meaty foods. They should, however, be fed regularly to keep them from becoming aggressive towards their tank mates. Emerald Crabs are particularly effective against bubble algae. There is a reason emerald crabs are so popular; they are very easy to care for, require almost no attention, and are effective in in controlling pesky algal blooms hence keeping the tank clean. The Royal Urchin, Mespilia globulus, is also known as the Globe Urchin, Sphere Urchin, Blue Tuxedo Urchin, and Tuxedo Pincushion Urchin. It has brilliant bands stemming from its center across a dark blue background giving it a look as though it is dressed in a tuxedo, hence some of the common names. This collection of pattern and color makes the Royal Urchin a fantastic addition to most reef tanks - it really stands out. It is nocturnal and will hide among rocks or substrate during the day and come out at night to feed on algae. They are able to kept successfully in pairs as long as there is enough room in the tank to move, places to hide, and algae to eat. If low algae levels are present, they can be supplemented with other herbivorous food preparations. Overall, the Royal Urchin is an exciting and unique invertebrate that is reef safe and easy to care for. The Dolabella Sea Hare, Dolabella auricularia, also known as the Wedge Sea Hare, is one of the best algae-eaters in the home aquarium. The Dolabella Sea Hare can clean an entire 125 gallon reef tank of all hair algae in about two weeks - they are quite the efficient janitors. They are rather sensitive to pH and salinity changes and can take a little while to fully acclimate to a new tank (they should be drip acclimated). Featuring a dulled grey color and soft spiky appendages, the Dolabella Sea Hare makes for an interesting invert.