In the Magyar Nemzeti Galéria in Budapest (Hungary), this oil-painting from an anonymous artist shows Saint Martin sharing his mantle with a beggar. The painting is dated 1483 .
In the foreground, lower-right, a snail is illustrated. The sinistral shell is stylised, the aperture detached, seen in top view. The animal either has two tentacles or two snail heads are shown in side view (the quality of the illustration unfortunately doesn’t allow to make out; I couldn’t find the painting in the online collection of MNG and the email I sent remained unanswered).
 RKD, art work 223702. http://explore.rkd.nl/explore/images/223702 (permalink).