Robuta

https://www.wish.com/product-reviews/1-x-silicone-chocolate-mold-brick-square-shaped-ice-jello-building-blocks-mold-shipping-method-568e36f5d322ff4881e375a2

https://www.trend.az/world/russia/3877232.html

https://www.nps.gov/articles/000/how-do-square-blocks-become-round-rocks-on-mount-desert-island.htm