“The biggest of the eggs was about the size of a football,”
“You need the right air temperature (below zero, but only a bit), the right water temperature (near freezing point), a shallow and gently sloping sandy beach and calm waves, maybe a light swell,” he said.
“You also need something that acts as the core. The core begins to collect ice around it and the swell moves it along the beach, forward and back. A small ball surface gets wet, freezes and becomes bigger and bigger.”