Jerome Muchnick said Wednesday that his grandson, 23-year-old Roger Muchnick, grew up in Westport, Connecticut and was a graduate of Staples High School.
"He did two stints in Afghanistan and came home," Jerome said.
The lifelong Philadelphian and prominent businessman is devastated by his grandson's death. Jerome said Roger survived two tours in Afghanistan in recent years, so he was relieved to have the young man stateside.
Now, he is struggling to come to grips with the cruel reality of what happened.
"I'm actually grateful that he didn't make it, because he would be the last guy that could be bedridden or without limbs. He was a jock, he was on the move all the time," Jerome said.
Roger was an outstanding football and lacrosse player in high school and played on his college lacrosse team. Then, Jerome said, Roger decided he needed more discipline and enlisted in the Marine Corps.
He was due to get out of the service this summer and, over Thanksgiving dinner, he told his grandfather he was going back to college.
"He was a respectful, loving, decent, kind human being. He was a great guy," Jerome said.
The Marines killed on Monday night were based at Camp Lejeune, N.C. The explosion's cause remains under investigation.
"I think it's very worthy of an investigation, and I think the parents of all these young men will feel the same way," Jerome said.
Funeral services haven't been announced.
Profiles of 7 Nev. Army depot explosion victims
A mortar shell explosion Monday at an Army depot in Hawthorne, Nev., killed seven Marines and injured eight other servicemen. Here are profiles of the victims:
AARON RIPPERDA, 26
Ripperda was a football player while he attended high school in Highland, Ill., near St. Louis. He was respectful and hardworking, according to Highland High School Assistant Principal Karen Gauen, and "definitely had the discipline for the military."
Ripperda had dreams of becoming a professional chef. His aunt, Beverly Lesicko, told the St. Louis Post-Dispatch he joined the Marines for a chance to explore the world. He was scheduled to come home in May.
JOSH TAYLOR, 21
Marine Lance Cpl. Taylor, who worked with mortars and served tours in Afghanistan and Kuwait, had dreamed being in the Corps since watching the History Channel as a boy. He joined right after graduating from a high school in Marietta, Ohio, in 2010.
Taylor's grandfather, Larry Stephens, said Taylor was engaged to be married, with a wedding planned for May.
His fiancee's father called him an exceptional person.
"You don't meet many young men like him today," Keith Malone told The Marietta Times. "He was respectful to everyone, very humble, just happy, happy all the time."
Taylor is also survived by three sisters and a brother.
ROGER MUCHNICK, 23
Muchnick, who'd been in the Marines for about three years, had served in Afghanistan and was considering returning to college after his enlistment was up. He played high school lacrosse and football in Westport, Conn., and later played lacrosse at Eastern Connecticut State University, where he studied business.
In a biography on the university's website, Muchnick said the one thing he would like to do before he died was "live," and his most embarrassing moment was getting caught lip-synching in a school talent show.
"He was at the top of his game when this happened," said his grandfather, Jerome Muchnick. "You can't imagine losing a very handsome, 23-year-old grandson who was vital and loving."
JOSH MARTINO, 19
Pfc. Martino, who hailed from Dubois, Pa., and was preparing for a deployment to Afghanistan, aspired to be a Marine since boyhood.
"Since he was probably 8 years old he wanted to be a Marine," said his mother, Karen Perry. "That's all he wanted to do."
Martino was a talkative former high school athlete and accomplished hunter who hoped to marry his fiancee later this year, Perry said.
His mother said she first heard a radio news report about the Monday accident, then three Marines arrived at her workplace to say her son was among the seven dead.
WILLIAM TAYLOR WILD IV, 21
Lance Cpl. Wild joined the Marines shortly after graduating in 2010 from Severna Park High School near Annapolis, Md. His mother, Elizabeth Wild, said he was in a weapons platoon that was scheduled to deploy in November to Afghanistan. He already had been deployed twice to Afghanistan and once to Kuwait.
Wild said her son always wanted to go into the military, like his father, who is a command chief in the Air Force Reserve at Dover Air Force Base in Delaware.
DAVID FENN II, 20
Lance Cpl. Fenn, who was from Polk City, Fla., enlisted with the Marine Corps in June 2010. He was promoted to his current rank nine months later. Fenn, who served as a mortarman, received numerous accolades including a Combat Action Ribbon and National Defense Service Medal. He was last deployed in 2011 to Afghanistan.
MASON VANDERWORK, 21
Lance Cpl. Vanderwork, who was last deployed in 2011 to serve in the war in Afghanistan, was a native of Hickory, N.C. Vanderwork joined the Marines in June 2010 and was promoted to his current rank by August 2011. He received several awards including the National Defense Service Medal.