I have some of these also. As Greg mentioned they reproduce quite rapidly, and when they attach to a rock they are very hard to remove. Mine came in as a hitchhiker on a coral base. Now I have about 20 of them scattered throughout my tank.
People tell me that they are mini maxes but I thought mini maxes were bigger in diameter, as these are the size of a loonie/toonie I wonder if there is a market for them
Here are the ones I have...
As compared to a mini max that I have, three inch diameter...
