I have had small mussels that came attached to live rock as hitchikers, and they have lived for years...in fact, I think they are still alive now. I have also had oysters last for years...one is hidden in a cluster of mushrooms and zoe's, andone year I accidentally broke off its front half. It actually survived, grew back, and is still alive now. I only wish my other tank inhabitants were as hardy! I do feed phyto almost every day, alternating ESV, 2 little Fishies, and Kent...take care, Eric