Some glaciers have wandering balls of moss, nicknamed glacier mice.

On Alaska’s Root Glacier, researchers tracked them moving in similar directions, averaging about 2.5 centimetres a day.

Each little green ball can also shelter tiny animals.

Little balls of moss wander across a glacier

Small green moss balls scattered across the ice of Alaska’s Root Glacier

Small green moss balls scattered across the ice of Alaska’s Root Glacier — Tim Bartholomaus

A glacier moss ball marked with coloured beads beside a ruler during field research

A glacier moss ball marked with coloured beads beside a ruler during field research — Tim Bartholomaus

Research maps track glacier moss ball positions from June to August; colours show dates and the right panel enlarges a cluster

Research maps track glacier moss ball positions from June to August; colours show dates and the right panel enlarges a cluster — Hotaling, Bartholomaus and Gilbert, Polar Biology (2020)

Little balls of moss wander across a glacier

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