Known. Skulls of crested geese were found in a 17th-century toilet pit.
The skulls come from a settlement at Flecken Zechlin, in Brandenburg, Germany. They date to the 17th century. Each skull has an opening that matches the crest on some living domestic geese, a tuft of feathers on the head. The marks are not from butchery, weather, gnawing, or disease. The page says these are the earliest crested geese yet found by archaeologists in Europe. The skulls were thrown away with ordinary kitchen waste.
The page does not show that the skulls were a special offering. They may simply be rubbish, and more study is still needed.