a beautiful Easter Andrew 
Your guess is right, theese are quads. This whole thing behaves with textures similar to the quadmesh thing although the quad-divisions are not exact the sames as with SubD for example. Usually you start with any simple rectangle - here you don’t have to draw any mesh yourself. After that ClWorks offers its own subdivision mechanism. You just have to decide how fine the divisions should get.
You can let the physical simulation run and stop with a play stop button. On the far right of the menu is a button which jumps the geometry back to the starting position.
In this starting position you apply your desired texture too. This “reference state” is always maintained, no matter where the simulation stops by itself or is stopped by you later.
At first the whole thing seems a bit clumsy and angular - but then you use CW’s own subdivider algorithm, which smoothes the resulting geometry. A second subdivider algorithm ensures that corners which have been rounded now become angular again…