Hmmm... They're warm. But they definitely look and feel man-made and they look pretty ghastly, not as 'Cath Kidston' as you might imagine. Because they have no shape, they don't stay put, not in bed, not as slipper socks, and not inside wellies. They arrived absolutely filthy and I would have sent them back had it not been the day my boiler broke down! Despite my complaints, my feet were very grateful for them that day!