The official description simply reads:
"A high quality, surrealistic set practical as a floor cushion.
Over-sized pebbles, a resting area with varying sizes and shapes that can be arranged according to your mood, for contemporary interiors.
Pebbles as a fanciful landscape for ideal and permanent holidays, which can be transformed into an enjoyable domestic game."
Well, the description doesn't quite do them justice, perhaps some complications there in the French to English translation. Anyhow, who needs a description, just look at them:
Livingstones, les coussins galets - Decoration interieure et exterieure