When provoked Cylisticus convexus can roll into a flattened ball, but its antennae and long pointed uropods remain protruding. This latter feature and its five pairs of pleopodal lungs readily differentiates it from Armadillidium spp. and Eluma caelata (which have truncated 'square' uropods and two pairs of pleopodal lungs).
Distribution and Habitat
It is widely, but patchily, distributed throughout Britain and Ireland and is equally at home in sparsely vegetated semi-natural coastal habitats and synanthropic sites inland. Coastal habitats include ‘soft’ cliffs, unstable screes, shingle beaches, erosion banks and salt marshes. Inland it colonises railway sidings and embankments, disused quarries, colliery spoil, farmyards, urban waste ground, rubbish tips, churchyards and gardens.
It is typically found beneath stones, dead wood and among strandline material and other debris.
This summary is based on the detailed account in Gregory (2009).