A fairly well-known phenomenon in geology, it forms with the evaporation of infiltrated water and is made up of sand and gypsum.
To put in a cabinet of curiosities.
To learn more about this phenomenon, you can consult the Wikipedia page here.
Approximate dimensions of the roses: largest, 11 x 8 cm. The other 3 vary from 7 to 8 cm x 4 to 5 cm.
