Tremella mesenterica (common names include yellow brain, golden jelly fungus, yellow trembler, and witches’ butter) is a common jelly fungus in the Tremellaceae family of the Agaricomycotina. It is most frequently found on dead but attached and on recently fallen branches, especially of angiosperms, as a parasite of wood decay fungi in the genus Peniophora. The gelatinous, orange-yellow fruit body of the fungus, which can grow up to 7.5ย cm (3.0ย in)