The Cottesloe waters were so calm last weekend, with very little swell coming in. Visibility was fantastic, possibly 4-5 m or more. So naturally, I had some good time snorkeling and checking out marine life. The highlight last weekend had to be these two nudibranchs Mexichromis macropus (3-4 cm in length) that I found at about 4 m's depth. They were grazing away on a small patch of blue sponge.
The arrow is pointing at the animal's exposed gills. Close-up, it looks like a piece of candy!