kreisel
n.β Β«Instead of rectangular tanks, she and her partner, Debbie Melechinsky, use a piece of 10-inch PVC pipe to round out the corners of the tank. Itβs called a “kreisel,” from the German word for carousel.Β» ββAquarists discuss safe breeding of seahorses” by Hannah Hickey Monterey Herald (California) Dec. 9, 2004. (source: Double-Tongued Dictionary)