Exidia nigricans

Exidia nigricans is a species of fungus in the family Auriculariaceae. In the UK, it has the recommended English name of warlock's butter. It produces black, gelatinous basidiocarps (fruit bodies) and is a common, wood-rotting species throughout the Northern Hemisphere, typically growing on dead attached branches of broadleaf trees. It has been much confused with Exidia glandulosa.