Yes, you've read it correctly, it's a soup made from stone found on the sea bottom.
So finally you find yourself relaxing on a beautiful beach of Starigrad Paklenica after day spent hiking in the National Park. The sun is burning and the view of the surroundings is stunning. There are many sea urchins in the water which means that the sea is perfectly clean.
After swimming you start to feel hungry. It would be great to catch a fish or two but you didn't bring any fishing gear with you what so ever. Limpet can do really well in nice risotto, but it's too hard to detach them even with a knife.
Stone soup! That's it! You just need to dive into the sea and find a perfect stone. It needs to be honeycombed with some inhabitanats, like clams and shrimps, in it. As for the rest to finish the soup you will need some onion, tomatoes, potatoes, carrots, olive oil and some spices. Everything needs to be boiled on light fire until cooked. Take the stone out, strain the soup, add some rice to it and voilà, as funny as it sounds your stone soup is ready.