Algodoo

It's a triangle. What do YOU think it is?

Its Triangle because it has three corners

Okay, all kidding aside, here is why those triangle-shaped objects skim across the surface of the plane. The user "greenrid" added a simple script to each triangular object which forces the angle of the object to always be zero. This is the script: angle = 0

When the angle of an object is forced to be a certain value, it will always try to remain in that orientation no matter how much external force is applied to it. The triangular shaped objects in this scene will always attempt to remain standing on their pointed end of the triangle shape because that's what the script is forcing them to do. BUT they are not perfectly upright. They are leaning to the left or to the right slightly. Because they are leaning, Algodoo attempts to return them to the position that the script is forcing them to (in this case it's zero). Each time they rotate slightly because of gravity pulling them in the direction they are leaning, Algodoo attempts to bring them back to the zero angle point. This battle of lean-correct, lean-correct, lean-correct, happens very quickly, many times per seconds, and that oscillating motion is what causes the object to appear like it's skimming across the surface of the plane.

That is what I believe is happening.