ProcessExplorer found it on the first try.
In the words of Private Hudson in Aliens
2, "Stop your grinnin' and drop ya linen! I found them!"
The mystery icon is Glary Utilities CheckUpdate.exe, the bottom line in the attached pic.
A mere "Thanks, and--well done," is not enough.
So, in the dry pro-speak and deadpan vernacular of 2001 A Space Odyssey's screenplay
POLITE APPLAUSE. FLOYD
WALKS TO FRONT OF ROOM.
First of all, I bring a personal
message from Dr. Howell, who
has asked me to convey his
deepest appreciation to all of
you for the personal sacrifices
you have made, and of course
his congratulations on your
discovery which may well prove
to be among the most significant
in the history of science.