Boudin filling rolled into a sphere, battered, and deep-fried is called a boudin ball.
It is a Cajun variation on boudin blanc, the Louisiana sausage made from pork, rice, onions, and seasonings. Instead of being stuffed into a casing, the mixture is shaped by hand, coated, and fried until crisp outside and tender inside.
Boudin balls are especially associated with Acadiana and are commonly served as snacks, appetizers, or convenience-store and restaurant foods. The filling can vary: traditional pork boudin may include liver or other offal, while seafood versions may use crawfish, shrimp, or crab.
A common mix-up is treating the dish as an ordinary croquette or arancini. Those foods share the fried, filled shape, but the name boudin ball specifically identifies the Cajun boudin filling and its Louisiana culinary tradition.