Yes, you read that correctly. The following fungus is called witches’ butter. Tasty! It also goes by a lot of other names apparently: yellow brain, golden jelly fungus and yellow trembler. In Dutch it’s simply called gele trilzwam. Latin name: Tremella mesenterica.
This is a fungus I found in a forest at Massembre, Les Ardennes. As you can see on the photo, it was on a dead piece of wood lying on the ground, covered with moss.
Wikipedia indeed confirms it lives on recently broken off, dead branches. It’s mostly visible after a rainy period, during which it expands it’s jelly body. When it’s been dry for a couple of days, it shrinks back until it’s nothing more than a thin, shriveled mass. The colour also darkens. According to Wikipedia, it should be edible, but I was never tempted to try that out.
The fungus can be found in Spring and Fall and can grow to be 5 cm diameter.