This fossilized shell came from an old shallow seabed which is in the middle of Ayrshire and proves Scotland was once tropical. It is made of limestone.
These fossils are older than the dinosaurs by about 105 million years. In fact, the estimated date for the area is 330 million years.
This piece is probably some kind of vegetation from the seabed. We found lots of Crinoid Stems in the area, as well as other, rounded shells.
Someone with good fossil knowledge will probably know instantly what type of shell it is. We picked it up in July 2021. It was the day of the bad sunburn.