Round, green / brown thing high in sycamore tree

Round, green / brown thing high in sycamore tree

Observation - Round, green / brown thing high in sycamore tree - UK and Ireland. Description: About three inches across. Green / brown sphere with regular marks or raised dots. Appears to be a h

About three inches across. Green / brown sphere with regular marks or raised dots. Appears to be a hole in the bottom. Hanging high in sycamore tree.