Pebble

A pebble is a rock with a size of 4 to 75 millimeters (some say 64 millimeters).

Pebble tools are among the earliest known man-made artefacts, dating from the Palaeolithic period of human history. They have been found at Olduvai Gorge (1.85 million years ago), and at Longuopo in China (1.8 to 1.5 MYA). Pebbles have many uses, such as weapons, floor coverings, etc.

See also: gravel