Armina babai grows to 50 mm in length and appears flattened, elongated, and narrow posteriorly. It has a yellow sole and smoothmantle. Longitudinalridges are absent, as is other ornamentation. The body itself appears ashy to whitishgrey and is translucent. There are two big spots on the notum that are purplish. The head veil is an ashy colour and has papillae that are dark brown. The anterior gills are yellowish white while the posterior gills appeardark purple. The viscera are pinkish in colour which sometimes show through the body. In some specimens, there are yellowish brown smudges that can be seen around the edge of the mantle.