Great challenge Jim (Raven)
congratulations teekay, Sibil, JimAskew
teekay's Seashell was my favorite too.
Mi entry is an old archive photo from my first Por1, processed in PhotoShop and stripped the exif info as was my usual workflow at that time.
Below, the exif, copied from an almost identical process of the picture in Light Room.RAW file.
Canon PowerShot Pro1 | fixed lens @23mm | 1/20 | f/3.5 | ISO 50
With this challenge, the first thing I thought of was a sunflower to show the golden ratio / Fibonaci numbers in the seeds array. No sunflowers in the archives.
Then a thought in fractas and OhLook mentioned them, luckily before any search in the Hard Drives.
Then I found this green 'thing' that was an alternative entry in other challenges, but never was posted because I have no idea of its name although it growed in my own garden. In our city, we have 'plants', 'trees', 'flowers' but we do not learn the names of them. 
By the way, OhLook, your coaliflower reminded me of Mandelbrot sets / fractals that I used long time ago (in the 70s) under the direction of Mesisas Maiguashca
as part of his show of electronic music. Maiguashca is a well known (and controversial) ecuadorian musician that lives and works in Germany.
BTW it's really good to see you back in a challenge with your Pro1, Rafael, and thanks for keeping the winners list up to date all these years
I always check and enjoy the challenges, but I comment usually when I have my own entry uploaded.
Well done everyone worthy winners and some great photos.I must admit not being a mathematical person so struggled to find something that really fitted in here.
