Myxarium nucleatum (Crystal brain fungus)

Myxarium nucleatum (common names crystal brain or granular jelly roll) is a jelly fungus in the family Hyaloriaceae. The sporocarps (fruit bodies) are watery white and gelatinous with small, white, mineral inclusions. It is a common, wood-rotting species in Europe and North America, typically growing on dead attached or fallen branches of broadleaf trees.

— Wikipedia