The Basic primordial beej mantra is “om”, it's the mantra from which all another mantras were being born. Every single beej mantra has a certain god or goddess associated with them. The kinds of beej mantras are— Yog beej mantra, Tejo beej mantra, Shanti beej mantra, and Raksha beej mantra. https://www.youtube.com/watch?v=7yoEpl90KUg