Wormies and bugs

[JPeDumont]

Today I noticed two weird black bugs on my sand... one looked like a small worm (a bristle worm, perhaps?), One was a cross between a small roach and a worm. And then there where the white wormies.... I guess one of my snails had died, cause coming, no swarming, out of he shell where a lot of little 1/4 inch white/clear worm looking things... then i noticed that there were all over the glass, eating the small concentrations of algae.

I'm not too worried, should I be? Are these guys common or good?

Thanks,
JPeD