Read more about this fascinating creature on Marine aquarium society of Australia’s Wiki.
The Sun Coral is a non-photosynthetic calcious coral that captures its preys by grabbing them with specialised stinging cells called nematocysts at the end of each tentacle. Read more about them on Wikipedia.
Super close-up photo of a single polyp of Goniopora sp. coral. Successful husbandry of this beautiful coral is still a mystery. Wikipedia.