These look like cloves polyps bit grow really large. They add a nice amount of movement to a softy tank and reflect the blue lights so they look blue. 

These won't sting other corals and make a great beginner coral!

    Approx 7 - 8 polyps

Picture taken under a Kessil AP700 Led fixture 

 Reef Gardener Inc is a Florida licensed aquaculture facility, certificate #AQ0623486