It’s a bag of Twiglets. These were particularly hard to get a good image of – they are mostly air. Too penetrating X-Rays (too high accelerating voltage) just passed right though with almost zero contrast. Too low, and I just got dark splotches where individual twiglets crossed over each other and increased the X-ray attenuation.
Interestingly, the metallised plastic package is almost invisible in this image. The micron thick layer of aluminium is really providing no appreciable X-ray attenuation.