Hi Oak333,
Note that apart from the bija mantras of the chakras there are other sets of bija mantras as well, which is used in Tantra for aspects such as healing, spiritual growth etc. Also remember that all bija mantras are always preceded by the Om which is viewed as the original bija from which All originated.
Bija mantras, when correctly applied, intoned and invoked can be extremely powerful. It is part of Tantra yoga and fascinating once you understand it.
One of the other spellings of bija is also beeja, again translations are problemsome as Nichole has already pointed out.