Made in solid cast oxidized Sterling the "stones of choice" for Primordial were fossil fish vertebrae that keep on it still sand residue from where they rested until found. It is not Incredible that we can touch, have, something that exxisted millions of years ago? I'm in awe, every-single-time... 
Set as coins are in a ring with prongs that allows us to see the back of them as well, the vertebrae elements hang fixed -soldered- to the sterling earring body with ear posts that secure on the back with pressure sterling nuts -that small curls- and as an addition, some of that silicone small tops that can be used to secure the nuts or to wear with them instead of like me, you feel ear nuts a bit uncomfortable for long wear.
Absolutely ancient looking, cast with ancient techniques and minimal tools -I love exploring ancient metalwork and learning old techniques where machinery was inexistent-, this are medium to small size -for my usual standard- filled with character.
For measurements, the pictures where the earrings rest on the bust show their real size since it is a human size mannequin, some of the other pictures include a standard size business card, a USA quarter coin and a ruler to allow you to have as much idea of their real size as I possibly can provide. 
If you need some metric measurement just let me know.