Nembrotha milleri is a large polycerid, exceeding 10 cm in size. Its distinctive characteristics are the following :
- the green body is covered with dark, almost black wrinkles
- the gills consist of 3 basal stalks splitting into five branching gills. The stalks are green and the rest of the gills is black
- the rhinophores are black with green base

Nembrotha milleri, like all other species of this genus, feeds on ascidians.

African Indian Ocean