Stock Photo - People walk around stone mushroom rock formations near the town of Beli Plast, some 160 kilometres (100 miles) south-east of the Bulgarian capital Sofia. The protected site, which has a total area of 3 hectares, was declared a natural landmark by a Government order in May, 13, 1974. The rock formations, made from intensive underwater volcanic activity, have the shape of natural mushrooms - their stalks are pink, and the caps are green. The height of the mushroom stalks and the width of the caps are up to 2.5 metres (8 feet). The lower, pink layer proved to be softer and more amenable to the effects of sun, wind and rain. The upper, green layer contains solid minerals, mainly volcanic glass and it is therefore more difficult to weather. So a wonderful combination of unique shapes and colors has formed over the millennia. Featuring: Bulgaria's Stone Mushroom Rock Formation Where: Beli Plast, Bulgaria When: 25 May 2015 Credit: Impact Press Group/WENN.com