The “cross gurgity” or “cross gurgitée”, while appearing in modern heraldry texts [e.g. Leonhard 291], does not seem to have been actually used in medieval armory. Its use is considered a step from period practice.
Gwynneth Sanquebarr bears: Azure, a fess argent between two crosses gurgity Or.
Uther Schiemann der Hunt bears: Gules, a cross gurgity Or within a serpent in annulo head to base argent.