A former New York City firefighter has turned to the Internet to search for the helmet he wore on 9/11.

ABC 13 reports that Michael O'Connell, 39, served as a New York City firefighter for nine years. The helmet that he wore while assisting with recovery efforts at ground zero after the September 2001 terrorist attacks was stolen from his home, along with medals and other valuable items.

The burglary occurred in 2012, and O’Connell has since been able to get the medals replaced.

But the helmet remains missing.

O’Connell was forced to retire at the age of 33 after contracting an autoimmune condition believed to be connected to occupational hazards he encountered.

O’Connell would like the helmet back to give to his children. That’s why he posted a photo of his son wearing the helmet on his Facebook page, and encouraged everyone to share the post.

While the helmet has not been found yet, people from around the world are sharing the post on social media.