Natural compass

Lichens are successful partnerships between a fungus (which forms the structure) and an algae (which photosynthesises, thereby providing the power source, sugars). Lichens often have very particular environmental requirements. Golden-coloured species such as this Leafy Xanthoria ( Xanthoria parietina) typically grow in sunny positions – which, in the UK, means facing south. In turn, this implies you can use lichen as a navigational aid!