If you mean the crescent shaped pasta (sometimes with ends touching), made from rolling a circle of pasta over the filling and then pinching the ends, then 'tortellini'
Ring-shaped soup pasta. Smaller than anelli siciliani but larger than anellini.
~Tortellini: small ring-shaped stuffed pasta ~Bucatini: is like a hollow version of spaghetti ~Trottole: comprise pasta rings that are curied around a central column
A ring shaped coral reef is called an Atoll.
There does not appear to be a city in Italy named Tortellin according to Google Maps. The word tortellin likely is referring to the word tortellini which is a ring shaped pasta.
Atolls
annulus
Tortellini are ring-shaped stuffed pasta. Cotechino is an Italian sausage, and "lenticchie" means lentils.
The 33 ring-shaped bones of the spine are called the vertebrae.
A ring shaped coral island found for from land is called an atoll.
a molecule, shaped like a ring
atolls
Atoll.