This reminds me of the stone “pillows” Egyptians and Mesopotamian cultures used.
https://www.ancientpages.com/2018/06/18/why-did-ancient-egyp...
I rather like my soft pillow and have a hard time imagining using a hard ceramic/stone pillow. But these ancient civilizations did it, some for thousands of years. Maybe there is something to it and it isn’t as uncomfortable as it seems?