Nudibranch - Phyllodesmium jacobsenae

This nudibranch - Phyllodesmium jacobsenae mimics the host, Xenia Corals which is also its food source.
In the picture, there are 2 of them. The one on the left is clearer to see as its rhinopores and oral tentacles can be clearly seen. The second one on the right is rested with its rhinopores and oral tentacles retracted and hidden, making them hardly visible as separate animal to the Xenia corals.

To better see this Nudibranch, here is another picture of them :