River jelly lichen  (Collema dichotomum)

This lichen is restricted to sites in Scotland, mid Wales, the north and west of England and Northern Ireland. It is also found across northern Europe and Russia.

The river jelly lichen has a preference for usually silica-rich submerged rocks such as sandstone, that form slabs in partial shade. It is typically found in swift-flowing rivers, but very occasionally it also grows on submerged rocks in upland tarns.