Coral is such an interesting structure. It is essentially a really complicated geometric skeleton for tiny animals. The geometric nature is that makes it so interesting, it is like the honeycomb of the ocean and it is beautiful in its ridges and voids that are extremely delicate but reinforced with naturally occurring math.
Nikon 1 AW1, Nikkor 11-27.5/f3.5-5.6 AW
27.5mm, f5.6, 1/640 sec @ 800 ISO