Why is iMovie showing more clips on my SD card than I thought there was?

Why is iMovie showing more clips on my SD card than Photos or other apps, and how do I add them to my device? I connected my olypus tough TG-6 to my mac, and iMovie's import page opened, and then I saw photos which I didn't remember taking with my camera. But when I tried to save it through Photos, it wasnt there. It wasnt there either in OM Workspace. It is still visable through iMovie's import page, but I can't even add it to a movie. can someone help me out? By the way, I am using a Macbook Pro 2015.