These two pretty shells, from the Lettered Olive family, belong to me and I have not been able to find much information about them. Each one is a little over an inch long. I don’t remember where I found them, but most likely on Sanibel Island or possibly Fort Myers Beach in the 1980’s.
Sea Shell City has a page of Olive shells for sale and this one is pictured, along with others. Even if you don’t want to buy one, the photos are very good.
Gibbose or Gibbosa Olive
The Baily-Matthews Shell Museum is located on Sanibel Island, Florida and this page lists Shell Idenitfication books and a POSTER with seashell photos and names. They also have 15 pages of shell pictures and their scientific names, but no search bar so you have to scroll through all the pages to find what you want. I didn’t find this brown olive shell listed.
[...] Florida Lightning Whelk - A ”left handed” seashell Natica Lineata & Babylonia Spirata …Shells with stripes and spots Pink Murex - A large shell Strawberry Conch -Small cone Lettered Olive & Golden Olive Sand Dollars- More than one type Jingle Shells- Iridescent Elegant Dosinia -or Disk? Pen Shell- Can be a foot long Jujonia -A treasure Spiny Jewel Box Star Fish/Sea Stars Gibbose (Brown) Olive Shell [...]