Pebbles

As rivers and waves roll them over and over, knocking against sand and other stones, their sharp corners wear away, a process that can take hundreds or thousands of years. A cairn is a pile of stones stacked up by people, often to mark a trail.

Drag a pebble to lift it and set it on the sand or on another stone. A careful stack stands; one set on the edge topples. The ✋ button turns this off, and reset puts every stone back. Tap it and five pebbles hop one at a time onto a cairn, biggest at the bottom, then all hop back. Pick a pile or a cairn in the Splash tab.