Wren's Nest National Nature Reserve is a geological site of exceptional importance and is one of the most notable geological locations in the British Isles. It is internationally famous for its large numbers of beautifully preserved Silurian limestone fossils. Wren's Nest supports a diversity of rare flora and fauna, due to the species-rich limestone grassland and ash-elm woodland. Several county rarities are present, including autumn gentian, small scabious, common gromwell and bee and pyramidal orchids. Some of the underground workings have since become a hibernation site for seven species of protected bat, whilst the locally uncommon white-letter hairstreak butterfly is also present in small numbers.