Euphyllia - This variety of hammer coral has a neon green coloration and a lot of fluorescence under actinic lighting. These specimens are cultured and not taken from the reef. 

Give this stinging species plenty of space to grow away from other corals. 

Hammer corals need moderate lighting and water flow. It's necessary to maintain stable alkalinity, calcium, magnesium, and trace elements. Be sure to acclimate new coral to bright lighting slowly and carefully.