The Structure and Distribution of Coral Reefs noted the location of the different types of coral around the reef and in the lagoon. In his diary, he described, "examining the very interesting yet simple structure & origin of these islands. The water being unusually smooth, I waded in as far as the living mounds of coral on which the swell of the open sea breaks. In some of the gullies & hollows, there were beautiful green & other colored fishes, & the forms & tints of many of the Zoophites were admirable. It is excusable to grow enthusiastic over the infinite numbers of organic beings with which
Open brain coral lobed. They typically have bilateral symmetry. During the day when the polyp is closed, the coral is covered by a mantle that extends beyond the skeleton, but can retract when disturbed. Polyps and mantle are very fleshy. Colonies can be blue, green, yellow, brown, and are often vibrantly colored. The open brain coral is known to host a species of gall crab, "Lithoscaptus" "semperi." Open brain corals can be found throughout the Indo-Pacific, from the Red Sea to New Caledonia. They are found up to a maximum depth of 40 meters. Open brain corals are less common directly in coral