Monsoon Aquatics from Darwin Australia posted these amazing videos to their Facebook Page of spawning Euphyllia paraancora. The videos clearly show egg bundles accumulating in the hammer shaped tentacles before being released through the polyps central mouth.
At least 30 colonies of all different color varieties started spawning on April 27th follow by a second spawning event on April 28th. Within 20 minutes 200 pieces of branching hammer coral started releasing eggs causing a chain reaction of coral spawning.
The gamete release happened at the same time both days, when the temperature was at its warmest. Monsoon also reported that certain individual colonies also started releasing sperm, and that there were even a few colonies releasing both sperm and eggs.
Some of these colonies were moved into holding tank to promote fertilizations, and we will see in the days to come if spawning fertilization was successful. It could be weeks before newly settled polyps are visible but this is nonetheless a very exciting observation on the spawning of branching hammer coral.