In the collection of the Rijksmuseum Amsterdam, this engraving by Etienne Delaune (1518–1583) is from a series of six on sciences represented by a woman . In this case astronomy is illustrated with various measuring devices, set into a frame with mostly symmetrical figures (inter alia two snails).
The snails are stylised, with two tentacles, an eye-spot and “dripping tails”. One shell is dextral, the other sinistral; both have wings but also a flower protruding from these. Is this what may be called ‘grotesque’?
 RMA, inv. RP-P-1964-2365. http://hdl.handle.net/10934/RM0001.COLLECT.413590.