Cratera imbiri is a flatworm around 26–38 mm in length and 2.5 mm in width. The body has parallel margins and rounded tips. The dorsal side of the body has a sulfur yellow median stripe that's bordered on either side by a khaki grey band. The body margins are a cream color. The front of the body fades into a coral red color on both the dorsal and ventral side. The rest of the ventral side of the body is cream.[2]
Aside from its coloration and length, it is distinguished from other members of Cratera by having marginal eyes, a cylindrical pharynx with the dorsal insertion posteriorly shifted at about a fifth of the pharynx's length, a pharyngeal pouch that is very close to the prostatic vesicle, the epithelium of the penis papilla being underlain by a circular muscle fiber layer, a female atrium that is 3.2 times longer than the male and gradually narrows at its posterior, and the presence of a long common glandular ovovitelline duct.[2]
