Agents Of SHIELD: 8 Ways It Sets Up Marvel's Inhumans
3. Terrigen Crystals
The Terrigen Crystals are inside of the Diviner, and they are what release the Terrigen Mists that cause dormant Inhuman genes to be activated. It was Skye and Rainas exposure to these in the Kree City that led to them being transformed, but also resulted in the death of Trip.
When mixed with the Diviner metal, the impact on those without Inhuman DNA is that they are petrified, and turned into stone. However, at the end of the season, the Terrigen Crystals - outside of the Diviner - were dropped into the ocean, which contaminated the fish that later became fish oil tablets circulated around the world.
While these tablets should be harmless to anyone without the latent abilities, it means that anyone who does have them will be transformed by taking the capsules. This opens the door for a lot more Inhumans to enter the world, presumably with really high-levels of Omega-3.