Hammer corals are an iconic large polyp stony coral (LPS) that has been a staple in the hobby for generations. They are found all throughout the Pacific reefs and come in a variety of colors and growth forms. Hammer corals sometimes grow in a wall formation while other hammers grow in a branching formation. Either variety makes an excellent show piece coral for a reef aquarium however the branching varieties tend to grow more quickly. Some aquarists observed clownfish host in large colonies. This may be suboptimal as the coral tends to shy away from constant contact from the fish. Hammer corals like all Euphyllia are known to extend sweeper tentacles aggressively when situated too close to other corals. This hostile reaction can damage or kill nearby corals, so it is important to be aware of placement at all times.