Reef Invert.s by Anthony Calfo and Robert Fenner... Its a 3 volumes series. Has a ridiculous amount of awesome photos, and is very in depth as it doesnt cover corals or anemones. Im on the hunt for the 2nd and 3rd volumes now, "Reef Fishes" and "Cnidarians" both by the same guys. And @ almost 400 pages its a steal for the price. I just finished reading it (god im a nerd) and i only got it 2 days ago. 8 of 10 in my book. If anyone knows where to get the other two volumes in the series (The Natural Marine Aquarium) Please reply or pm me. This ones worth checkin out. You may have read one of his volumes on Coral propogation, quality stuff.