A Double Torus

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A double torus can be obtained by plotting the following function (thanks to H. Karcher):

     z = Sqrt[-x^4 + 2*x^6 - x^8 + 2*x^2*y^2 - 2*x^4*y^2 - y^4 + (2/10)^2]

Spikey Created with Wolfram Mathematica 9.0