This is a classic French peasant home sink. Two well-worn flat slabs, one on either side, and a slightly hollowed one in the middle.
Mine has a tiny bit of decorative bevelling on the front of the three stones, but often they don't even have that. A funnelled part of the central stone projects outdoors to get rid of waste water.
The small glazed window I installed myself. The original was just a hole and was the size of a paperback; it allowed hardly any light in, and did nothing to stop any cold or wind. I cut the new one from a single lump of stone, and it looks a tiny bit better.
It wasn't so long ago that these sinks were still being used. The poor housewife had nothing but an adjacent open fire to cook on, and the sink was to prepare vegetables, do washing up, etc. It was also the family 'bathroom'.
Life must have been very tough for those hard-working women. Looking after the children, preparing all the meals, and probably attending to the kitchen garden, pigsties, chickens, ducks etc.
We don't know how lucky we are. Well, I suppose we do really!