PENSACOLA, Fla. — A Florida man who helped build the 21,600-pound bomb dropped on Afghanistan on Thursday said so many years had passed since the weapon was developed that he thought it might have been taken out of the military's arsenal.

Crestview resident Joseph Fellenz, who retired from the Eglin Air Force Base weapons lab in 2008, said his daughter called him and told him that an old photo of him with the weapon, knicknamed the "Mother of All Bombs," was on the national news.

"It was a real surprise," he said in a phone interview Thursday.

Fellenz, 70, spent more than 20 years developing weapons prototypes as a model maker at the lab.

The GBU-43/B Massive Ordnance Air Blast bomb was designed to replace another bomb known as the "Daisy Cutter" and put pressure on then-Iraqi leader Saddam Hussein to cooperate with U.S. forces, he said.

It was the largest weapon Fellenz helped make.

The Thursday bombing of an Islamic State tunnel complex in Afghanistan marked the first time the $16 million bomb was used in combat.

"It would have done some damage," said Fellenz, who thought the weapon might have been disarmed and taken out of military use.

"I was happy to see that it was used," he said.

Gen. John Nicholson, commander of U.S. forces in Afghanistan, said in a statement, said the bomb was the right weapon for the job.

"This is the right munition to reduce these obstacles and maintain the momentum of our offensive against (the Islamic State)," Nicholson said.