Bosellia mimetica is a species of sea slug, a marine gastropod mollusk in the family Plakobranchidae.

It has a rounded, flattened body and is a mottled green, a colour that mimics that of the algae Halimeda tuna and Flabellia petiolata on which it lives and feeds.

[3] Bosellia mimetica is a small, flattened sea slug that seldom exceeds 8 millimetres (0.3 in) in length.

[4][5] It can be distinguished from the rather similar but slightly larger Bosellia cohellia by the shorter rhinophores which lack white bands.

The white pigmenting resembles the worm tubes, bryozoans and other epibionts which occasionally occur on the host alga, and its specific name "mimetica" derives from this mimicry.