Weird 'Ice Boulders' Wash Up on Lake Michigan

They came on the tides by the hundreds – big, spherical clods of ice whose dirty-brown exteriors made them look like a platoon of Tribbles.

Presumably they're still around, entertaining people around Lake Michigan with their fun appearance and possible usage as nuclear-grade snowballs. Locals call them "ice balls" or "ice boulders," and though they might seem an unnatural, ominous formation to much of the world – something to be pushed back into the water with a bulldozer, perhaps – they've made many appearances in the history of the Great Lakes. Last February, for instance, a flotilla of basketball-sized orbs washed up in the Sleeping Bear Dunes National Lakeshore, allowing Traverse City meteorologist Joe Charlevoix to explain how they're formed: