Two pendants (very similar, but no total copies) are present in the Fritzwilliam Museum, both attributed to Justus van Huysum (I) [1, 2]. Both are flower still-lifes with a snail at the edge of the table.
Justus van Huysum was an Amsterdam painter (1659-1716), who was active in that city from 1674 until his death .
On the first painting, the snail is clearly a Cepaea species.
On the second painting, this is probably the same species, although the shell looks slightly more elongated. However, the quality of the image does not allow a higher resolution.
In the RKD database these paintings are both dated to the active period of this painter, viz. 1674–1716 .
 FWC, inv. PD.28-1975. http://data.fitzmuseum.cam.ac.uk/id/object/1592.
 FWC, inv. PD.29-1975. http://data.fitzmuseum.cam.ac.uk/id/object/1590.
 http://explore.rkd.nl/explore/images/119235 resp. 119236.