Corals

                                                                         Brain coral

                         Is formed by a colony of genetically identical polyps which secrete a hard skeleton of calcium carbonate; this makes them important coral reef builders like other stony corals in the order Scleractinia.



                        The Duncan coral is a beautiful, rare and hardy coral to keep. Although it is very similar to other large polyped stony corals in terms of tolerance and sensitivity many hobbyists fail to keep it alive due to its feeding requirements and due to poor water quality. Its tentacles are always extended, even at night, but if slightly disturbed, will readily retract them. 


                                                                        Xenia
                is a genus of photosynthetic soft marine coral resembling a mushroom, with "arms" coming out from the top that end in many-fingered "hands". It is unique among corals because of its ability to use its "hands" to "pulse" or push water away from the colony in a constant, grabbing motion. This action is unique to Xenia species, and was once thought to be used for catching ambient plankton, but is now thought to be used for respiration