I'd guess the shape is an ellipse. I remember learning way back in geometry that ellipses have special reflective properties: http://www.math.ubc.ca/~cass/cours

I'd guess the shape is an ellipse. I remember learning way back in geometry that ellipses have special reflective properties: http://www.math.ubc.ca/~cass/courses/m309-01a/dawson/ http://www.math.ubc.ca/~cass/courses/m309-01a/dawson/