A domed coral with deep winding valleys, the pattern the name describes. One of the commonest large corals on the reef.
Smooth flat plates or massive hemispherical domes up to 1.8 m across. Growth is about a centimetre a year, so a large head is well over a century old. The surface is covered in long sinuous interconnecting valleys holding the polyps, and the colour is yellowish or greenish-brown, occasionally blue-grey, with the valleys often a contrasting shade.
The identification is the ridge between the valleys: here it is smoothly rounded with no groove along its crest. The grooved brain coral has a distinct groove running along the top of each ridge, which is the cleanest single field mark among Caribbean brain corals. The knobby brain coral forms smaller, knobby, encrusting colonies with shorter, less regular valleys in shallow turbid water.
It is a framework builder and its polyps are mostly withdrawn by day. It reaches about 40 m and occurs on muddy seabed as well as on reef, which is unusual.
It is highly susceptible to stony coral tissue loss disease, dying in the first wave — a week for a small colony, one or two months for a large one — and it is one of the corals that visibly disappeared from Florida reefs from 2016 onward. Its conservation status is currently unclear: the long-standing listing is least concern, but a number of Caribbean corals were uplisted in the December 2022 reassessment and this one may have been among them.
The genus changed in 2012 and older books carry it under Diploria.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
