Hairy Green Mushroom Corals
Here is a hairy green mushroom coral (HGMC); brown mushroom corals can be seen to the left.
When the HGMC feels threatened, it extrudes its guts in protest. I've just moved some rocks around, and it is not happy with the mistreatment. The HGMC will suck its guts back in after a little while, and get on with life.
When the HGMC detects food on its surface, it [slowly] engulfs the food. Here we can see the process starting.
The engulfing process is proceeding.
From on top, you can see the ball formed by the engulfing coral, along with a view of its mouth, directly under the opening at the top. Notice the other HGMC's around the central one: they've not decided to engulf prey at this point.
Our engulfing HGMC, in the middle of a nest of other HGMC's. Flame scallop is in the lower right and anemone tentacles in the lower left.
Now, other HGMC's are starting to engulf food, too.
Here we finally have all of the HGMC's turned into balls, engulfing food. Macro algae can be seen to the left, and a fox coral to the right.
Here is a close-up of the outside of the HGMC ball: notice the complex structure.
A view from on top, with the mouth open inside the opening ball.