Shell Grotto at Margate (UK) In 1835 Mr James Newlove lowered his young son Joshua into a hole in the ground that had appeared during the digging of a duck pond. Joshua emerged describing tunnels covered with shells. He had discovered the Shell Grotto; 70ft of winding underground passages leading to an oblong chamber, its walls decorated with strange symbols mosaiced in millions of shells. Is it an ancient pagan temple? A meeting place for some secret cult? Nobody can explain who built this.