It appears to be a bolete covered with the white mycelium of a mycoparasitic fungus belonging to the genus Verticillium, a genus of conidial fungi. Same idea as the delectable lobster mushroom; a fungi-on-fungi arrangement.
An article on BBC's website July 11 2015 about the "Wood Wide Web" can be read here. It details many examples of mycorrhizae; communication between plants via mycellia.
The article provides a link to a 5 min documentary on the work of Prof. Suzanne Simard, UBC Faculty of Forestry, who studies the underground communication network of trees;
"Mycorrhizal fungi form obligate symbioses with trees, where the tree supplies the fungus with carbohydrate energy in return for water and nutrients the fungal mycelia gather from the soil". There is a substantial text entry attached to the You Tube post which is a good read.