Thousands of rare ‘ice eggs’ have appeared on a beach in northern Finland

The unusual phenomenon requires very specific conditions.

Thousands of unusual egg-like ice balls were discovered on a beach in northern Finland on last week.

Covering much of a beach on Hailuoto Island, near Oulu, the ice balls are formed when pieces of ice interact with sea water under the right conditions.

Images of these ice balls were first shared on social media by an amateur photographer.

An ice specialist from the Finnish Meteorological Institute said these ice balls were rare but not unprecedented, and could occur about once a year as conditions allow.