Hammer coral (Euphyllia ancora) can be quite variable in colorSeveral of the so-called large-polyp stony (LPS) corals offer the advantages of being very hardy, adaptable, and beautiful and, thus, make excellent reef aquarium candidates, even for relatively new reefkeepers. The hammer coral (Euphyllia ancora), however, I would characterize slightly differently. There’s no question this coral is gorgeous, but I would rate it as rather less forgiving than, say, Trachyphyllia geoffroyi. Still, if its care requirements and aggressive nature are given proper attention, this coral can be a showpiece reef aquarium resident. Physical traitsE. ancora has long, tubular tentacles with tips that resemble, as you might guess, the head of a hammer or an anchor. Most specimens I’ve come across have had brownish to grayish tentacles with the tips being some shade of green, gold, or cream, but the color can be quite variable. Colonies of this coral can get quite large—upwards of 3 feet across—which must be taken into consideration when determining tank size, placement, etc MORE