According to several industry figures who knew him personally, Ultimate Fighting Championship veteran and mixed martial arts pioneer Cal Worsham is dead at the age of 55.Fellow fighters including Shannon Ritch , who posted a memoriam on Facebook , and onetime opponent Gary Goodridge , who tweeted his condolences , have claimed that Worsham passed away Nov. 28 of a reported heart attack.A former United States Marine and a highly-ranked black belt in Tae Kwon Do, Worsham made his no-holds-barred debut at UFC 6 in July of 1995, losing to an opponent nearly twice his size in Paul Varelans From there, Worsham would fight in two more UFC events before embarking on a long career as a journeyman who was distinguished not only by his cachet as a UFC pioneer but by a penchant for action: At 13-10, he finished all of his victims -- all but one in the first round -- and only heard the final horn once in 23 professional fights. At Gladiator Challenge 67 in August 2007, he fought on the same card as his son Hunter Worsham , likely the first father-son duo to accomplish the feat. Both won their bouts.This story will be updated as appropriate if more information becomes available.