No they did not invent djent, but they were definitely one of the first few bands that help pioneer that style. Look it up.
"TesseracT, one of the U.K.'s pioneers of the exploding djent movement, have just unveiled the new music video for "Nascent"
-- From http://www.guitarworld.com/tesseract-unveil-new-video
"They are credited as one of the bands to pioneer the 'djent' movement in progressive metal."
-- From http://en.wikipedia.org/wiki/Tesseract_(band
"TesseracT have been a band for many years, and were sporadically releasing songs on the Internet to widespread acclaim in underground circles way before the multitudes of so-called “djent” bands they inspired even existed"
"One was released last year). This puts them in sort of a weird spot; it feels like they’re late to the game, and to the unknowledgeable observer it would certainly appear that way, even though they helped to create that game to begin with."
-- from Metalsucks
Also melodic death metal has several founding bands, In flames, Dark tranquility, At the gates.
There can be more than one band that pioneers a style.
so can we settle this now?