Zibellini (aka “Flea Furs”)
''Fleas, Fur, and Fashion: Zibellini as Luxury Accessories of the Renaissance'' in Medieval Clothing and Textiles 2

A website describing a mid-16th century Italian jeweled marten’s head at the Walters Art Museum describes one line of thought regarding the presence of this accessory in portraits of women:

“The marten was thought to conceive its young through its ears, free from sexual intercourse, and was thus associated with Christ’s miraculous conception. This symbolic meaning is indicated by the presence of the dove of the Incarnation on the creature’s snout. Such objects were fashionable in Europe during the sixteenth century. They also served as protective amulets for pregnant women.”

The medieval legend to which the Walters’ website refers is referenced in the story of Galanthis in Ovid’s Metamorphoses, and also in the Epistle of Barnabas. Although Isidore of Seville (Etymologies, Book 12, Chapter 3) asserts that “Falso autem opinantur qui dicunt mustelam ore concipere, aure effundere partum,” this legend continues to appear as a fact of natural history in medieval bestiaries (such as The Aberdeen Bestiary and a 15th century French bestiary [MMW 10 B 25, fol. 24v]), and is illustrated in the Queen Mary Psalter (see The Medieval Bestiary: Weasel).

This description seems to be a lot more realistic than the line of thought usually put forward by reenactors and/or costumers – that it is meant to attract fleas to the fur, rather than the wearer – a theory which appears (at the moment) on Wikipedia, as well as plenty of other websites. It does seem highly unlikely that wealthy women would wear an such an ostentatious accessory to advertise their personal vermin problems, though. It appears that the Italian word zibellino (pl. zibellini) may refer to most of the mustelids, and so may be a more appropriate term for this 16th century fashion accessory than “flea fur.”

See also The Muff in Sixteenth Century Dress.