Upon closer inspection, police found the steel was covering a cave surrounded by bits of human garbage. Officers then hiked for more than an hour through the dense vegetation and found Song hiding inside.
Song was grey-haired, dishevelled, and unable to communicate after years of isolation when officers found him, according to Yongshan police.
His cave was about two square metres wide, with steps out the front and a makeshift bed inside.
Song told police he had survived by collecting water in plastic bottles from a nearby stream.
He then confessed to escaping from prison and was taken back to jail.