Elysia timida is a species of sacoglossan sea slug, a marine opisthobranch gastropod mollusk.

[1] Found in the Mediterranean and nearby parts of the Atlantic, it is herbivorous, feeding on various algae in shallow water.

When the animal has been living in a habitat with Lithophyllum or other pink calcareous algae, the white colour may be tinged with mauve.

[3] It is found in sea grass beds and on rocks on which the algae on which it feeds is growing, at depths down to about 20 m (66 ft).

Elysia timida feeds on the alga Acetabularia acetabulum in spring and summer, and on Padina pavonica in autumn.