The essential primordial beej mantra is “om”, it's the mantra from which all the opposite mantras were born. Every single beej mantra has a specific god or goddess linked to them. The kinds of beej mantras are— Yog beej mantra, Tejo beej mantra, Shanti beej mantra, and Raksha beej mantra. https://yantra04836.thenerdsblog.com/32190309/a-review-of-beej-mantra