- "What are you doing with the helmet?"
"What, the -- the alien thing? I-it's a souvenir." - ―Phil Coulson and Tony Diaz[src]
The Chitauri Helmet is a component of the armor worn by the Chitauri soldiers as they invaded Earth during the Battle of New York. One such helmet was found by volunteer firefighters after the battle.
History
The Chitauri wore helmets during the Battle of New York.[1] After their forces were defeated by the Avengers, three volunteer firefighters named Adam Cross, Frank Whalen, and Tony Diaz helped in the clean-up efforts after the Battle. During the clean-up they found the helmet of one of the fallen Chitauri and decided to take his helmet as a souvenir.
A few months later, when they started to clean what they thought was rust, they liberated a virus carried by the wearer of the helmet, that sequentially killed Cross, Whalen and Diaz, and infected Agent Jemma Simmons of S.H.I.E.L.D.
The Chitauri virus present in the Chitauri helmet
When Agent Phil Coulson's team recovered the Helmet, they transported it to a S.H.I.E.L.D. facility called the Sandbox that dealt with biological threats.
Upon arriving at The Sandbox, Agent Felix Blake's team took custody of the helmet.[2]