Lemniscate

In algebraic geometry, lemniscate refers to any of several figure-eight or ∞ shaped curves, of which the best known is the Lemniscate of Bernoulli. It is also sometimes used to refer to the infty symbol used in mathematics as a symbol for infinity. lemniscate is like a butterfly. Look at this picture below:



Lemniscate is a simple lemniscate can be described graphically by the following equation: 2(x2 + y2)2 = 25(x2 − y2)
(Source: http://www.xhumanhealth.com/1307/lemniscate/)