The Crystal sea slug, Janolus cristatus - June 2015
An image entered in the British Society of Underwater Photographers (BSoUP) monochrome competition. This is the Crystal sea slug, Janolus cristatus.
This nudibranch was photographed in Northern Ireland on the wreck of the Lochgarry near Ratlin Ireland.
Nikon D600, Nikkor 105VR, +5 dry diopter