Five fishermen depart from a harbor in a 17-foot open boat on a calm morning. Within hours, a violent storm hits. The boat vanishes. Nine years later, the boat is found washed ashore on a deserted atoll 2,300 miles away. Near the boat, a grave is discovered containing one man's remains and a stack of blank paper interleaved with small squares of tin foil. No writing appears on any page. Investigators determine the papers are a specific type of ritual offering associated with East Asian funeral customs. What are these papers called, and what is their purpose in the burial tradition?