The Basic primordial beej mantra is “om”, it's the mantra from which all the other mantras had been born. Each beej mantra has a particular god or goddess connected to them. The types of beej mantras are— Yog beej mantra, Tejo beej mantra, Shanti beej mantra, and Raksha beej mantra. https://www.youtube.com/watch?v=7yoEpl90KUg