A Navy veteran is suing after what his lawyer describes as a 16-pound pine cone fell and crushed his skull in San Francisco.

The San Francisco Chronicle reports that Sean Mace is suing the U.S. government, the National Park Service, the Department of the Interior and San Francisco Maritime National Historical Park for $5 million.

Mace's attorney Scott Johnson says the veteran was relaxing under a non-native pine tree at the maritime park when the cone fell, causing an irreversible brain injury. Johnson says Mace has had two surgeries and requires a third.

The park has already fenced off the grove and added signs warning "Danger: Giant seed pod falling from tree."

Representatives from the U.S. attorney's office and San Francisco Maritime National Historic Park did not return requests for comment.