The presentation of a de luxe comb of elephant ivory by Archbishop Riculf of Mainz to his friend Alcuin of York in c. 794 provided the occasion for two replies, one in a prose letter and the other in a verse epistle, in which Riculf's gift is playfully transformed into the subject of a descriptive riddle. This pair of short texts-hitherto neglected by riddle scholarship-show the Anglo-Saxon riddle mentality at work in the transformation of an artifact into an animate being, whereby the various elements of the comb are described in terms of the head and mouthparts of a formidable creature. The texts are discussed in the context of the Anglo-Latin riddle-form, and I show that the verse version in particular has affinities with the vernacular riddles of the Exeter Book in its use of a narrative frame and conventional closing formula. Although elements of Alcuin's riddle are elucidated by examining early medieval combs of the type in question (in particular the large ivory comb deposited with the body of St Cuthbert in the late seventh century), some enigmas remain.