Solar powered sea slug

Just enjoying an afternoon with some algae when I notice there's something on my Bryopsis plumosa specimen that isn't Bryopsis plumosa. It's about the size of a Grape Nut and perfectly camouflaged, but I abduct it with my eyedropper and put it in a dish to examine under the microscope...It turns out there's about four of these little guys on my sample. Placida Dendritica to be more precise.

(it could fit in this "O")

And they are all busy siphoning chlorophyll from my Bryopsis to fuel their own photosynthesis. Craziness. Especially because I can't stop thinking about how much they look like the forest spirit from Miyazaki's film, Princess Mononoke.