A suncup is a small depression on the surface of snow or firn. They are formed by the melting and evaporation of the snow / ice surface by insolation (warmth from direct exposure to the sun.)
Photo of suncups on the surface of a snow patch in the Italian Alps. The cups measure approximately 30cm across and are at least 45cm long.
The photograph was taken at the end of September 2006 after the snow had been exposed to insolation throughout the summer.
A small snow patch in the Italian Alps (photographed in late summer 2006) exhibiting suncups across the surface.