The huge Stone mushrooms (2-3 m height) are situated north of the village of Beli plast, just along the main road from Haskovo – Stremtsi – Kardzhali. Their age is from 35 million years ago when the Rhodopes were a bottom of a warm sea. Then underwater volcanic activity started and shaped the rock. When the water moved away, the climate formed the rocks into mushrooms. They are even colored with the right painting – pink for the stumps and dark green/grey for the hats – because of the different minerals in the rock of course.