After two weeks of bottle conditioning, I brought two bottles upstairs only to notice small dark particles floating around in both bottles. It seems like the particles are stuck to the sides, then when the bottles are disturbed, they start falling to the bottom. These don't really look like yeast to me, they look darker and larger, but I'm not experienced enough to say for sure. Otherwise the beer is clear in both bottles. Does it sound like it's safe to test one?