What Is The Small, White, Gritty Kind Of Stuff After Sex ?

After sex, my partner noticed a small, white, gritty kind of stuff all over the bed under the area we had just had sex. He wondered if it was all just some sort of dirt, not at all from after having sex. But since it was white, odor-free and gritty/soft, I don't know what it is. I just explained as though my secretions of wetness (from being aroused) mustve "balled-up" and came out in small gritty for as he was thrusting.
Am I right? What could that be? I'm a little embarrassed too.
Thanks!