No, they are not "doughnuts" - but they look similar. The glass ring with the hole in the middle floats on the water and the last flower from your bouquet has a new home. Pretty wonderful in large bowls in combination with the Float (Art. 854), Bubbles (Art. 859 and Art 859.1) and the Swimming Frogs (Art. 853).
Glass tubes and glass rods blown and shaped at the burner- so-called "lamp technique”.