And the Sisters Islands are just teeming with hard corals of all kinds.
It was particularly rich in mushroom corals today!
Corals are colonial animals and each colony is made up of tiny animals called polyps.
In many, the polyp looks like a sea anemone with a ring of tentacles around a central mouth.
Each polyp creates a hard skeleton.
The patterns of the colony is the result of the different shapes of these tiny skeletons. 
The brain coral does indeed look like a lobotomy job! This one is probably Symphyllia sp. Scientists usually identify hard corals by the structure of their skeletons. So when the animal obscures the skeleton structure, it's hard to be sure of the identity of the hard coral.But here's some corals on Sisters Island that are quite easily identified even when they are alive.
Branching Acropora sp. corals are always a delight to encounter as they are rather rare on our more accessible islands. Unfortunately, this was the only colony I saw today.
Carnation corals (Pectinia sp.) have thin fluted skeletons so that the entire colony does resemble a carnation.
There were several large colonies of this hard coral on Sisters Island, in various colours. This hard coral is not often encountered on our other reef flats.
Lettuce coral (Pavona sp.) has colonies with leafy structures. The individual polyps create the typical pattern in the photo on the right.
In Galaxy corals (Galaxea sp.) each polyp creates a skeleton with a star-pattern at the top. This is not so obvious when the animals extend their tentacles.The Sisters Islands are a haven for mushroom corals (Family Fungidae). And there lots of them on the reef today.
This disc-shaped animal is not a colony but one giant solitary polyp. Adult mushroom corals are not attached to the surface! In the photo on the left is a mushroom coral that was found lying upside down. I turned it the right way around after taking the photo. In the photo on the right is a happy mushroom coral with its tentacles extended.
Mushroom corals, however, start their lives attached to a hard surface. Such as these tiny little ones seen today.
Here's one really TINY one. This is why we should not step on crunchy coral rubble and step only on sand when exploring the reef.
Here's two stuck together, possibly they split apart when they were smaller?
And there were lots of very pretty big ones everywhere.
Crowded together in probably the best mushroom spots!Compared to our last visit to Sisters, there seemed to be a lot more sand in the big lagoon. Also, some of the corals seem to be a little sad, although still alive. But there were a lot of little baby corals even beyond the mid-water mark.
Only one large colony was seen with signs of bleaching. 
And one large patch of zoanthids (a relative of the hard corals) seemed to be diseased.
