Our saltwater aquariums are teeming with fish, corals, and a whole slew of beneficial aquarium cleaning invertebrates. These are clearly visible and are usually the focus of our attention, but look a little closer to find the nearly microscopic life that fills our sand beds. You don’t need a magnifying glass, just a little patience and a keen eye. The sand is full of worms, starfish, snails, and tiny crustaceans scurrying about and are often one of the indicators of aquarium health. Most of these critters will hitch a ride into your aquarium on a piece of live rock or a coral frag, but they can also be purchased from the right source.