Branching Flowerpot Coral - Alveopora sp.

They are not flowers but a coral colony. Alveopora (Scleractinia - Poritidae) is a genus of stony corals with at leas 27 nominal species, all of them native to the Indo-Pacific.

These corals create branched and massive skeletal formations, which are light and porous. They are generally clear coffee, cream or green, and can have shades of pale pink, yellow or blue. Their oral disc and the tips of the tentacles can be green or white. The contrasting color of the oral disc and tentacles give them the look of  flowers. 

Alveopora possess 12 tentacles and their corallites have 12 septa. Polyps may reach 30 cm long or more. The Branching Flowerpot Corals extend their polyps both during the day and partially at night.

References: [1] - [2]

Photo credit: ©Daniel Stoupin | Locality: Australia