The Chilostoma zonatum flavovirens or granite helicon

No, it's a snail, not a musical instrument! This relatively rare mollusc which can reach 2 or more centimetres in diameter is seldom seen in the Pays des Écrins, but appears to enjoy living in the Fournel valley. It takes shelter among cool damp boulders which are, as its name suggests, non-calcareous... Something quite unusual for snails, whose shells are made up essentially of calcium carbonate!