Alot of corals release "spores" or sperm and eggs at certain times of the year. I think it has something to do with the moon as to when it happens... Now depending on what type of brain it is you can manually make more of them by fragging.
thats what i was thinking. i wonder if the are like nems where if you catch part of the mouth they will reproduce? prolly not tho. i never see anyone fragging brains.