Unidentified fungus

Unidentified fungus

Observation - Unidentified fungus. Description: This yellow fungus was found at the base of a young ash tree in a new (10 year old) woodland. Cutting off a section revealed the inside to be white and fibrous, very light and similar to polystyrene! Any suggestion please?

This yellow fungus was found at the base of a young ash tree in a new (10 year old) woodland. Cutting off a section revealed the inside to be white and fibrous, very light and similar to polystyrene! Any suggestion please?