Sounds like those deadly miniature limpets i saw on Discovery. (cellana mortifica) Found in the tropics, and are the latest species to be blamed by scientists for demise of the reefs, exceeding the ability of crown of thorns strafish to devour corals. About the size of a match head, they peproduce contnuously and grow to adult stage within a few days. Furthermore, they also release a deadly toxin into the water, which paralises corals defenses against them. They feed only at night, ( a hint that they do have a natural predator, but yet undiscovered by scientists) hence you wont see them in your tank during the normal photoperiod. Turn over some rocks and you will see them swarming, just DONT TOUCH THEM!!!! Miniature swarms of them have benn observed paralising and consuming fish whilst sleeping as well.
If you thought that was scary, read on......
Their venom is rated as more powerful than that of the blue ringed octopus, and a bite or contact with a wound on human skin can cause the worst. Even if only the water they are in comes into contact with scarred human skin, as an unfortunate scientist found out. I was searching around reefing cyberspace and found a few cases where entire tanks were crashed, mass moratilities and wipeouts attributed to these little buggers and even hobbyists spending some time in in ICU.
So in essence, NO, they are not reef nor reefer safe!!!!!
Got you worried? could not resist the temptation. Imagine if they really existed.... What you have are miniature limpets, or stomatellas (shell shaped more like an abalone than a limpet) totally reefsafe, good algaevores.
Cleaner shrimps and wrasses love them, so yes, thats why you dont see them in the main display. Try having a look it the middle of the night, you should see them on the glass.
