It comes in a blue sausage-shaped wrapper depicting the product's name in black letters within a white rectangle in the middle. On the back, there are nutrition facts listed. Food-wise, it is most likely a sausage-like treat, given the shape of the wrapper.
Role in the episode
When Karen points out to Plankton that provision of food-rich environments causes amoebas to reproduce after the latter examines Spot with an X-ray, the scene pans to a pile of all the food Plankton has been feeding Spot lately, one of which is Uncle Moe's.