An Italian receipe collection was trusted to vellum in the late 15th century in Naples . One of the receipes was for cooking snails, and perhaps to ascertain that the scribe was not misunderstood, a sketch of a snail was added.
The snail has an eye-spot and two bat-like ears (meant to be the larger tentacles); the shell is just a blob.
 PMM, inv. Ms. B.19, 90 ff. [corsair.themorgan.org, search ‘snail, #18]