There's no stone left unturned in Italian artist's workshop

Luigi Lineri's home work-shop is covered in stones - tens of thousands of them. They resemble animal heads, human faces and other forms, and the artist and poet believes they may have been shaped by prehistoric humans.

Lineri has built his vast collection over the last 50 years, making his finds along the Adige river, near Verona in northern Italy.

"I haven't counted them and don't intend to do so but the quantity is significant," Lineri says.