This unusual animal related to nudibranchs slipped into our aquarium unnoticed as a tiny juvenile on some algae we collected. It continued to feed and grow happily on the algae until it got big enough to notice one day. It is Oxynoe viridis and has a thin clear shell with blue spotted animal to match his many other blue spots including the trim on his long trailing foot. He was nearly an inch long (25mm).
23 November 2015