Saxamo!

Euphylla Ancora, also known as Hammer Coral, Ridge Coral, Hammerhead or Anchor Coral, is a large polyp stony (LPS) coral. Its common names are derived from the appearance of its hammerhead or anchor-shaped tentacles. Its polyps are visible throughout both day and night and hide its skeletal base. They breed via fission, which is a form of asexual reproduction and each resulting fragment produced is capable of growing into an individual.

Hammer corals may be green, tan or brown in color, with lime green or yellow tips on the ends of its tentacles, which glow under actinic lighting. Some varieties of hammer coral may be branched, which makes them look similar to Torch Coral. They can appear semi-transparent when well expanded. Hammer coral colonies may form continuous cover over the substrate many meters across, although individual colonies are seldom over one meter across. Large colonies are usually found in shallow environments exposed to moderate wave action. Hammer coral does well within a range of at least 75 to 84 degrees and prefer moderate light. (A good example of moderate light is a 65 watt light over a 25 gallon aquarium).

Keeping Hammer coral in a saltwater aquarium is not recommended for those new to the hobby. This is mostly because their delicate nature makes them rough shippers. Hammer corals have sharp skeletons that are covered in extremely thin tissue, which is inevitably easily scuffed by shipping. All Euphyllia should be given plenty of room to expand in an aquarium setting. Sweeper tentacles extend several inches at night and can sting other corals.

Hammer Coral Aggressiveness and Feeding
Hammer coral can expand considerably from its skeleton and has sweeper tentacles that are up to 2″ longer than normal tentacles that can sting its neighbors. Hammer corals grow fairly quickly and to a large size. It is photosynthetic and does not need to be directly fed, but will take small meaty foods if offered. Hammer coral is aggressive toward the other marine aquarium invertebrates.