Postia caesia
The polypore mushroom Postia caesia exhibits blue-gray color tones,
has a soft and spongy consistancy
, a fuzzy cap surface and grows on
wood.  
Mature examples (pictured above; 8cm) develop a sharp cap
margin and a gray to blue-gray pore surface.
Oligoporus caesius is a
synonym.
See Oligoporus caesius at
Fungi growing on Wood
Very young examples (2cm) of Postia caesia and its habit of
formation along the side of a hardwood log, possibily
sycamore.
Postia caesia often grows in over-lapping groups, but
single specimens may also be found.
The blue-gray spore deposit and sausage shaped spores
(4-5 x 0.7-1µ) of
Postia caesia.