Desert rose is the colloquial name given to rose-like formations of crystal clusters of gypsum or baryte which include sand grains. The ‘petals’ are crystals fanning open in radiating flattened crystal clusters. The rosette crystal habit tends to occur when the crystals form in arid sandy conditions, such as the evaporation of a shallow salt basin. The crystals form a circular array of flat plates, giving the rock a shape similar to a rose blossom.
info: wikipedia
Rob Lavinsky, iRocks.com – CC-BY-SA-3.0, CC BY-SA 3.0, via Wikimedia Commons
Didier Descouens, CC BY-SA 4.0, via Wikimedia Commons
Laura Peña, CC BY-SA 3.0, via Wikimedia Commons
Rama, CC BY-SA 2.0 FR, via Wikimedia Commons/
Lichtbildner: Sven Teschke, CC BY-SA 2.0 DE, via Wikimedia Commons
e MORFES 
Lovely ! In French, we say “Sand roses”… I have got one at home.
I love these