To describe the skeletal formation at the aboral side of a recently settled scleractinian cold-water coral Caryophyllia huinayensis individual, adults were collected in Comau Fjord, Chile, and transferred to the experimental aquarium facility of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research. Released larvae were collected and placed into glass flow-through cubes (2 cm side length) made by cover slips, and kept until larvae attached. Post-larval development was documented photographically. For this purpose, the cover slip with a settled larva without exposure to air was placed under a stereomicroscope (Leica MZ 16, Wetzlar, Germany) with a Leica camera (IC80 HD; Wetzlar, Germany) attached. The photos of the aboral pole of the polyps were each taken from the same distance and angle and document the basal plate, septa, and columella formation by the growth of the translucent aragonite crystals. However, some polyps formed an opaque layer on the aboral side over time, impairing the observation of the inner structures.

Photos show aragonite crystals forming the basal plate at the aboral side of a recently settled larva of the scleractinian cold-water coral Caryophyllia huinayensis. The image sequence shows the increasingly difficult observation of the inner skeletal structures (septa, columella) of a recruit 6 days, 32 days, and 84 days after settlement.