Hammer corals (Euphyllia ancora and related species) are large-polyp stony (LPS) corals recognized for their distinctive hammer- or anchor-shaped tentacle tips that sway gently in the current. They come in a range of colors like green, gold, and purple, and are prized for the movement and visual interest they add to reef aquariums. Hammer corals can form branching or wall-type colonies and are generally considered moderately easy, making them a popular choice for reef keepers. Care GuideHammer corals prefer moderate lighting and gentle to moderate, indirect flow that allows their tentacles to fully extend without being blasted. They need stable water parameters (temperature ~76–80°F, salinity ~1.025, alkalinity 8–9 dKH, calcium 400–450 ppm, magnesium 1250–1350 ppm) and are sensitive to rapid changes. They can extend long sweeper tentacles at night, so give them space from other corals to avoid stinging. While they rely on photosynthesis, occasional feeding of small meaty foods like mysis shrimp can support growth and health.
