@hunter-thurmond if you’re looking for an inexpensive option to take close up shots of fossils with your iPhone, I can’t recommend the mPow lens kits enough. They are very affordable, and clip onto your phone camera lens. I know that some folks take issue with the fact that it can “bend” the image, but it does a pretty job good for the price tag.
Amazon link for mPow lens: http://a.co/hUO9I7O
@tmorgan might have a suggestion as she uses an interesting set up/attachment on her smartphone, if I remember correctly. @dellingson also uses iPhone lens attachments, and took some fantastic photos of fossils using his set up during a field trip in Nebraska, so he might want to chime in, too.