The Fundamental primordial beej mantra is “om”, it is the mantra from which all one other mantras ended up born. Every beej mantra has a certain god or goddess affiliated with them. The categories of beej mantras are— Yog beej mantra, Tejo beej mantra, Shanti beej mantra, and Raksha beej https://www.youtube.com/watch?v=7yoEpl90KUg