Old boules

Herbert Wegner has the most interesting, complete ànd multilingual site about "boules cloutées" (nail studded boules), the forefathers of todays' pétanque boules.
The wooden core made them relatively light, but the nails gave them a hard shell and prevented them from breaking up.
He describes the history, different makes and varieties.
An online museum so to speak.

Boules cloutées (click on the British flag)