It is food made for amoebas that comes in a brown can. On the can, the product's name is transcribed in lime green lettering within a white square. Below this is a pink amoeba.
Role in the episode
When Karen points out that provision of food-rich environment causes amoebas to reproduce after Plankton examines Spot with an X-ray, the scene shortly pans to all the food Plankton has been feeding the latter lately, one of which is Chow.