The island was made a Site of Special Scientific Interest because of its maritime life. This includes internationally rare lichens; bryophyte, plants, bird species; and intertidal communities. Nationally important flowering plants include sharp rush, rock sea lavender, small adder's tongue, western clover, and the rare purple loosestrife. Two nationally rare heathland lichens are found on the slopes of "Mynydd Enlli": the ciliate strap lichen and golden hair lichen; and there are over 350 lichen species in total. The leafcutter bee, which cuts neat, rounded circles in rose leaves, used to seal the entrance to its nest, is native.