Hairy shells appeared to be the ancestral character state in the genus Trochulus, a feature which has most probably been lost three times independently.

It had been previously hypothesised that these costly protein structures of the outer shell layer facilitate locomotion in moist habitats.

The possession of hairs facilitates the adherence of the snails to their herbaceous food plants during foraging, when humidity levels are high.

The absence of hairs in some Trochulus species could thus be explained as a loss of the potential adaptive function linked to habitat shifts.

[5] Trochulus species in moist habitats prefer to forage on large-leaved herbaceous plants like Adenostyles, Urtica (nettles), Homogyne or Tussilago (coltsfoot etc).