Lesser Knob Coral

About

The lesser knob coral (Cyphastrea japonica) is a small-polyped, hard coral native to shallow reef environments across the Western Pacific, ranging from Japan down through Java and Indonesia. In the wild it tends to grow in exposed, high-energy reef zones, forming submassive or encrusting colonies with an irregular, lumpy surface texture that gives the species its common name. The corallites are small and packed closely together, with toothed septa and prominent surface spinules that give colonies a rough, almost granular look up close. You may also notice characteristic groove-and-tubercle formations across the coenosteum, which add to that textured appearance. Coloration tends to run toward mottled cream, yellowish-green, or occasionally grey. Nothing flashy, but there is an understated natural quality to it. One honestly interesting trait: wild colonies are frequently colonized by parasitic barnacles, which is something to keep in mind if you ever inspect a specimen closely. In the aquarium, Cyphastrea japonica fits into the intermediate care bracket. It does not demand intense lighting or turbulent flow, but it rewards consistent water quality and stable conditions. If you enjoy working with small-polyp stony corals and want something a little different from the usual reef centerpieces, this encrusting species is worth a closer look.