My latest hitchhiker is the Stomatella snail from the family trochidae which is a harmless herbivore that (according to Chuck’s Addiction) has a unique way of fooling predators. “When attacked or pulled off the glass by us, it will drop a large portion of its foot, much like some lizards that break off their tails in an attempt to keep a predator busy while it makes its escape.”
It looks like a cross between a snail and a slug with a cap-like shell. The shell only covers a small portion of the animal which makes is somewhat vulnerable to predators. Stomatellas are herbivores and feed upon micro algae. They also seem to be multiplying in my tank. We noticed the first one within minutes after introducing a fairly large coral live rock in my tank. Within about 6 weeks we noticed a smaller one. The larger ones are approximately 1″ and the smaller about 1/2″.
You can read all of the details for these snails at Reef Keeping. According to Reef Keeping, “they are quite good grazers, and also reproduce well in aquaria lacking hermit crabs and shrimp predators”.
I most always see these guys at night after the lights have dimmed. They are methodically working the live rock for algae. More pictures are available at Reef Corner.