Image of blue-spotted sea hare

Description:

"Absolutely amazing to watch this. The round ""sand"" in the middle of the back gets popped out. This is one of a group of about 243 - that is all I could count. After a while with the ""sand balls"" popping out and holding their shape, fish came in (couldn't get a photo of them as they blended into the water and cause too much distortion) and ate what I am guessing is roe."