It is a dusty rune. That should have been their first clue that it was dangerous.
The Lost March is a large collection of elephant rafts. The lost march never reached its destination and instead was pulled out to sea. The elephants on the raft eventually starved to death, littering the large wooden carpet with their bones and bird picked hides. While sailors with an eye for gold can salvage the tusks of the bull elephant for a hefty price, the raft is haunted by the spectral ghosts of the pod of elephants and they appear after nightfall and attack and kill anyone trespassing on their raft