This engraving by Leonardo da Vinci (1452-1519)  is now in the graphical arts department of the Musée du Louvre. Baron Edmond de Rothschild donated it in 1935. The title is “Buste de vieille femme avec un casque” . No date is given in the description.
The snail in the helmet of the woman is sinistral, and although it is slightly stylised the four tentacles are clearly shown. The shell has slightly over two whorls, with the last one widening towards the aperture and showing a thickened lip.
 MLP, AG inv. 4066 LR. http://to.ly/xIGF.