Devon Cajuste -- the ex-Cleveland Browns tight end who became a fan favorite on "Hard Knocks" -- is retiring from pro football to focus on his true passion ... healing, spirituality and crystals.
And, if you watched the show ... this really shouldn't come as too big of a surprise.
When he wasn't battling for a roster spot with his father cheering him on ... Devon spent his free time during Browns training camp working with crystals and learning about healing.
In fact, one of the most memorable scenes from the show was when Devon showed off his crystal collection and explained how different crystals emitted different kinds of energy.