Egg-shaped curves constructed using multiple Circles which Thom (1967) used to model Megalithic stone rings in Britain.
See also Egg, Oval
References
Dixon, R. Mathographics. New York: Dover, p. 6, 1991.
Thom, A. ``Mathematical Background.'' Ch. 4 in Megalithic Sites in Britain. Oxford, England: Oxford University Press, pp. 27-33, 1967.