Renter: Snail shells. Empty snail shells of small to medium size species(e.g. Bulimus, Candidula, Helicella, Helicopsis, Monacha, Pomatias, Theba, Xerolenta, Xerophila, Zebrina). On the Kras (Slovenia) it uses snail shells of the species Pomatias elegans.
www2.pms-lj.si/andrej/snail.htm
LeGoff (pers.comm) reports nesting in shells of Candidula unifasciata in Seine Maritime (FR).
The closed shells are transported over a distance of up to 2.2m to a sheltered place, e.g. underside of a stone, below leaves or in grass tussocks; rarely, this transport takes place before nest provisioning. Occasionally, the shells are shallowly buried in loose soil.
Nesting material: The shells are closed with a three-layered plug consisting of a layer of small stones and earth crumbs delimited on both sides by a partition made of chewed leaves (e.g. Helianthemum) or petals (e.g. Lotus). The shell surface is densely plastered with patches of leaf pulp. (Banaszak & Romasenko, 2001; Bellmann, 1981; Benoist, 1931; Bonelli, 1971, 1972; Ferton, 1894, 1897, 1905; Gogala, 1999; Grandi, 1961; Grozdanic, 1969; Müller et al., 1997; Westrich, 1989; G. Le Goff, personal observation).