Seattle Seahawks safety Kam Chancellor, left, and cornerback Richard Sherman warm up with their teammates at the start of NFL football practice Wednesday, Jan. 29, 2014, in East Rutherford, N.J. The Seahawks and the Denver Broncos are scheduled to play in the Super Bowl XLVIII football game Sunday, Feb. 2, 2014. (AP Photo/Jeff Roberson)JERSEY CITY, N.J. (AP) — They don’t have a secret handshake, decoder rings or their own clubhouse. But even Groucho Marx, who refused to join any club that would have him, would have loved to get into the “Legion of Boom.”It’s not just the coolest club — with the coolest nickname — in the NFL at the moment. It’s also the most exclusive.You don’t have to be an All Pro-caliber cornerback or safety, as Seattle’s Richard Sherman or Earl Thomas are, but it helps. Membership is limited to the four starters, four backups and three assistant coaches who work in the Seahawks defensive backfield — the back end of the best defense in the league this season.Once accepted, you get bragging rights, a T-shirt and a floor mat to lay in front of your locker. It may not sound like much, but …“Be honest,” said Seattle’s Byron Maxwell, who stepped into a starting corner role when front-liner Brandon Browner was suspended indefinitely for substance abuse. “When you were little, if you heard the name ‘Legion of Doom,’ right away you’d say, ‘That’s a group I want to be part of.’”Yet there’s a group even the members of the “LOB” long to join. It’s the short list of great defensive squads with great nicknames that terrorized opponents AND went on to win Super Bowls.The best-ever moniker, “Monsters of the Midway,” belonged to arguably the best defense ever, the 1985 Chicago Bears. The 1986 Giants “Big Blue Wrecking Crew” probably should have won more than one. Ditto, perhaps for Miami’s “No-Names,” who won theirs the season after Cowboys coach Tom Landry described them this way — “A bunch of no names I really don’t know anything about” — and then beat them in the 1972 Super Bowl.In this Jan. 20, 1980, file photo, Los Angeles Rams running back Wendell Tyler (26) is thrown for 4-yard loss by Pittsburgh Steelers linebacker Jack Lambert (58) as Steelers; L.C. Greenwood (68), Gary Dunn (67) and Joe Greene (75) during first quarter of Super Bowl XIV at the Rose Bowl in Pasadena, Calif. (AP Photo/File)Two of the longest-lasting, Pittsburgh’s “Steel Curtain” and Dallas’ “Doomsday Defense” both won more than one in the 1970s.But just as long is the list of those that didn’t.The Vikings’ “Purple People Eaters” appeared in four of the first 11 Super Bowls, and wound up losing every one. Denver’s “Orange Crush” of late 1970s fame brought the franchise to their first championship, but went home empty-handed. So did Miami’s second entry, the “Killer Bs,” so named because the last names of six of the unit’s 11 starters began with that letter. Two more, the Rams’ “Fearsome Foursome” and the Jets’ “New York Sack Exchange” never made it to a championship at all.The eight current members of the “LOB” are young enough to rattle off the names of a few of their celebrated predecessors, but either don’t know their fates or don’t believe in omens. Truth be told, they’re all too consumed right now trying to fashion a legend of their own. The one thing all of them agree on is the founding member.“I did a radio interview a year or two ago talking about styles of play,” safety Kam Chancellor recalled, “and I was saying, ‘When we go to attack guys, we want to lay the boom on ’em.’ Fans who were listening started coming up with names for us. There was a bunch of ’em, I looked ’em over and said, ‘Not this one, not this one, or this one.’“But when someone said ‘Legion of Boom,’” he added, “I had to admit, it was pretty catchy. ‘Legion’ sounded pretty important, and the ‘boom’ was how we played, so we ran with it.“The really important part is that we, as a unit, were already connected. The brotherhood was already there. The trust, the drive, the passion was already there,” Chancellor said, “and ‘Legion of Boom’ turned out to be the icing on the cake.”So it was Chancellor, then, that came up with the T-shirts and mats.“No,” Chancellor laughed. “I got to give Sherm the credit for that. He’s the one that went the extra mile.”You might think the “LOB” unit within a unit would make the rest of the defense jealous.“No,” said linebacker Heath Farwell. “Just the opposite. They earned it. Those guys are an inspiration. The way they practice, the way they push each other to get better every day, it’s the kind of thing the rest of us can feed off.”But a moment later, Farwell changed his tune.“OK, I have to admit: the nickname really is pretty cool. We — the linebackers — tried calling ourselves ‘The Regulators,’” he added, “but so far it hasn’t stuck.”Thomas thinks that’s because nicknames have to happen organically.“You don’t give yourself one. You just don’t,” he said. “It has to come from somebody else, and it has to reflect something about you. … All of us in the (defensive backfield) love flying around and lowering the boom, so as soon as we heard it, we all just said, ‘Yeah, it’s a good fit.’”The Thomas who plays for Denver — that would be Demaryius Thomas, the Broncos’ 6-foot-3, 230-pound wide receiver — reluctantly agreed.“They call themselves the ‘Legion of Boom’ for a reason,” he said. “They are very physical. Everybody hits and makes tackles. Everybody plays aggressively.”But would they be just as fearsome by any other name? The question was put to backup corner Walter Thurmond.“How about ‘Nation of Domination?’” he replied.“Nah, Thurmond added a moment later, “we didn’t really consider any others.”___Jim Litke is a national sports columnist for The Associated Press. Write to him at [email protected] and follow him at Twitter.com/JimLitke.