I an Hughes and his son, Ben, are driving through the hills of north Wales with an array of homemade animal artefacts rattling around their car: diagrams, plaster casts, hand-printed T-shirts. They finally reach Llyn Tegid – Bala Lake in English – where, knee-deep in the water, Ian brandishes two glutinous snails. It is a mollusc the size of a fingertip. It is also one of Europe’s most endangered species, which Ian has dedicated himself to protecting. “It’s beyond passion,” he says. “It’s an obsession.” Glutinous snails get their name for the gelatinous, golden-flecked tissue that protects their shell. Because they live in low-calcium habitats, the shell is extremely delicate, so Hughes uses a fine paintbrush to move them from one place to another. The snails have been driven to extinction in England by the poor quality of the country’s freshwater bodies. Pollutants from agriculture and industry have ruined their habitats in ponds, ditches, lakes and streams.…