This is an exceptional, ex-museum, clam fossil!
Despite dating back 66-100.5 million years, half of this ancient shell still retains its lightly iridescent nacre (mother of pearl) coating.
Measuring ~5.25" long and ~4" wide, this would make a great addition to any collection.
It spent decades on display at the old Hobberlin Museum in Ontario, Canada.
Worldwide shipping is available!