Colony Polyp, Green are colonial animals with several individual polyps attached to a piece of live rock or coral rubble. They are bright yellow in color and their polyps have the ability to sting other polyps or corals. While the sting is not strong, they are semi-aggressive and need to have space between their colony and any neighbors.
Zoanthids are unique in that they incorporate sand and other small pieces of material into their tissue to help create their structure. In the wild, Zoanthids often occupy fringe environments (intertidal, back reef, other shallow areas, over dead corals), making them quite a hardy choice for the reef aquarist.
Easy to maintain, Colony Polyp Green require a medium light level combined with a medium water movement within the aquarium. For continued good health, they will also require the addition of iodine and other trace elements to the water. They will reproduce easily in the reef aquarium by budding (splitting off a portion of their base or mouth), which will increase the size of their colony.
They contain the symbiotic algae zooxanthellae which provide some of their nutritional requirements. They will also benefit from additional feedings of micro-plankton or brine shrimp given to each individual of the colony.
I wish I knew what kind they were. Kind of mixed in on a misc Zoo rock I bought for $10.00. Actually paid $50, but received 4 or 5 other frags and a Kenya tree for 50 total, so this probably equaled out to $10.