Flat Cup Coral

About

The flat cup coral (Acanthophyllia deshayesiana) is a large, solitary stony coral native to the Philippines and the South China Sea, where it lives on soft, deep-bottom substrates rather than the hard reef structures most corals prefer. That origin goes a long way toward explaining its care requirements in the aquarium. It wants low flow and moderate light, not the turbulent, brightly lit conditions you'd set up for, say, an Acropora. What makes this coral visually interesting is its coloration: concentric bands of pale and deep greens, reds, and browns, overlaid with radial striations that give the whole disc a layered, almost hypnotic look. The polyp itself is remarkably fleshy, with thick soft tissue that largely conceals the hard skeleton beneath. When you look closely at an exposed skeleton, the septa are dramatically uneven in size. The largest ones carry big, rounded teeth, while the smallest are nearly smooth. The columella at the center is dense and compact. Despite coming from deeper water, this species is generally considered a beginner-friendly coral, as long as you respect its preference for calm, low-flow areas of the tank. It is reef safe and not known for aggressive sweeper behavior that would threaten neighbors.