Lesser valley brain coral

The brain coral (Platygyra daedalea) needs no introduction: the surface of its rounded colony is covered in winding, interlocking valleys and raised ridges, eerily reminiscent of the folds of a human brain. The ridges are typically brown or grey-green while the valley floors are often bright green or cream – the contrast is what makes the pattern so hypnotic. Its scientific name "daedalea" is no accident: it honours Daedalus, builder of the Cretan labyrinth.

The winding valleys hold not single polyps but whole rows of them, fused together after losing their dividing walls: one valley contains a line of mouths sharing common tissue. By day the colony looks smooth; at night a forest of tentacles opens from the valleys to catch plankton – while daytime energy comes, as ever, from photosynthesising zooxanthellae algae. Brain coral grows slowly, only about a centimetre a year, so metre-wide colonies are patriarchs many decades or even a century old. On summer nights after the full moon it broadcasts its pink egg bundles into the water in a mass spawning.

It is common all over Hurghada's reefs, from the shallow plateaus to the base of the slopes – the most photogenic, perfectly spherical colonies sit on the plateaus of El Fanadir and Umm Gamar. It is a hardy species, but because of its slow growth every injury leaves a mark for years: an anchor or a kneeling diver punches a crater into a labyrinth built over decades. Keep your distance and leave the maze unsolved – untouched.