the.com/ammonite
a sea-monster spiral that ruled oceans for 300 million years, then died with the dinosaurs
Named afterEgyptian god Ammon's coiled ram horns
Living relativethe nautilus, their distant surviving cousin
Size rangefrom a coin to over two meters
Buoyancy trickgas-filled chambers let them hover like submarines
Folkloremedieval England called them coiled snakestones