Yes, those are your seeds.... how delightful that you saw them and saved them instead of just deadheading your plants.

That feathery tail... if the seeds fell to the ground naturally... would untwist during a rain and actually screw the seeds into the ground to plant them!

Check internet for information on planting them. I know that a lot of geraniums commercially offered for sale as bedding plants are grown from seed, and the bigger seed companies specializing in flowers sell geranium seeds. They AIN'T cheap!! If your plants are hybrids, the flowers you get may not be exactly what you saved seeds from, but you will still have the fun of growing them and seeing them bloom.

I have had a few (very few!) scented geraniums come up from self-sown seeds the following spring. As I recall, it was the "nutmeg" fragrance, which is a true species.

Jan, Arkansas Ozarks