In the Bibliothèque Municipal in Le Mans (France), the “Roman de Saint-Graal” is present as Ms. 0354 and is dated ca. 1285 . It is part of the Lancelot-Grail series of Arthurian legends, of which nearly 150 manuscripts are known. The project site can be found here . All manuscripts differs in their illuminations, so iconographic comparison is a job apart.
On f. 030r in the lower margin an illustration can be seen of a knight opposing a snail. The shell is sinistral and the animal has four tentacles, of which two are pointed towards the knight.
 Le Mans BM, Ms. 0354, 207 ff. http://bit.ly/1nDjNkw (2.ii.2014).