Polyabolo
An analog of the Polyomino composed of 
Isosceles Right Triangles joined along edges of the same length. The number of polyaboloes composed of triangles are 1, 3, 4, 14, 30, 107,318, 1106, 3671, ... (Sloane's A006074).
References
Sloane, N. J. A. SequenceA006074/M2379in ``An On-Line Version of the Encyclopedia of Integer Sequences.''http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S.The Encyclopedia of Integer Sequences. San Diego: Academic Press, 1995.
- Sphere Eversion
- Sphere Geodesic
- Sphere Packing
- Sphere Point Picking
- Sphere-Sphere Intersection
- Sphere with Tunnel
- Spherical Bessel Differential Equation
- Spherical Bessel Function
- Spherical Bessel Function of the First Kind
- Spherical Bessel Function of the Second Kind
- Spherical Bessel Function of the Third Kind
- Spherical Cap
- Spherical Coordinates
- Spherical Design
- Spherical Excess
- Spherical Frustum
- Spherical Geometry
- Spherical Hankel Function of the First Kind
- Spherical Hankel Function of the Second Kind
- Spherical Harmonic
- Spherical Harmonic Addition Theorem
- Spherical Harmonic Closure Relations
- Spherical Harmonic Tensor
- Spherical Helix
- Spherical Point System