Solitary Cup Coral

About

The solitary cup coral (Cynarina lacrymalis) is one of those corals that looks almost too good to be real. During the day it inflates its fleshy mantle with water, puffing up into a balloon-like dome that can appear translucent, allowing the thick, radiating skeletal ridges beneath to show through like the spokes of a wheel. That pattern, combined with colorations ranging from earthy greens and browns through to soft pinks and occasionally other shades, gives each individual its own distinct character. Come nightfall, the daytime display deflates and feeding tentacles emerge instead. Found across a wide sweep of the Indo-Pacific, from the Red Sea and the coast of East Africa all the way out to Tonga and up toward southern Japan, this species occupies protected reef zones and deeper sandy flats, which tells you a lot about what it wants in captivity: low flow and subdued lighting rather than the bright, turbulent conditions many reef keepers default to. It lives as a single polyp on a conical or cylindrical skeleton, either anchored to a hard surface or resting free on soft substrate. For a large-polyp stony coral, it is genuinely approachable for newer reef keepers, provided you respect its preference for gentle water movement.