Math in Second Life
This sim built by Henry Segerman (aka Seifert Surface).
The metal ball above the bridge is made of 4 nested spheres, rotating on different axes. Behind the sphere is a tower of octahedrons. (A octahedron is a regular solid, having 8 faces, each face is a equilateral triangle. (it's like two pyramids with their bases glued together)) On the right is a geodesic dome made of glass. Inside is a garden with mathematical sculptures.
For a particle version, see: Second Life: Math Lorenz Attractor.
The background blueish strip is the Moebius strip. Moebius strip is a example of a surface that has only one side. (If you are a ant crawling on the strip, you'll end up on the other side without crossing any edge.) The rim of this strip, is a Trefoil knot. Tie a overhand knot, then connect the lose ends, and you have it!
Try Xah Tele-Dasher!