You might think your lecturers know a lot of stuff. And so we do. But the stuff we don’t know is even more interesting. Liz Sheffield asked me whether fire corals (Millepora) have two multicellular phases of their life cycle with different ploidy levels (like a fern!) or if meiosis happens in the medusa and the only haploid bits are the single-celled gametes (like us). Given this wasn’t a question about flies or stegosaurs, I couldn’t answer it, but was pretty confident Richard Preziosi would know. But he didn’t either, and what’s more, he hasn’t been able to find the answer. In fact, he doesn’t know. But he does know that fire corals aren’t corals (which is also why common names aren’t always useful). True corals (and anemones) are Anthozoa and have no medusa stage. In fact, most true corals reproduce by fission. Fire corals are really more jellyfish type animals. They generally have no hard excreted skeleton and just a thin epidermis.
Pictures of fire coral and other stuff on diseases of coral (and fire coral can be such a disease) here.