SceneLayer objects can be animated by setting their anim attribute. There are many different animations available to choose from, however only a few of these will be of any real use in a level.
Most animations run quite quickly at their default speed (animspeed=1), so you will usually need to slow them down by setting the this to a number less than 1. You can use negative values to make the animation run in reverse.
In particular, rot_1rps is an animation with precisely 1 rotation per second. To make something rotate once every 10 seconds, set animspeed=0.1.
This appears to be named incorrectly, as it actually appears to do animation advance. In the video below, the object with animdelay=0.1 is ahead of the object with animdelay=0.
You may also notice that animdelay=0 and animdelay=1 give identical results.. in fact animdelay={x} seems to be the same as animdelay={x+1} (presumably the animdelay is a specified as a fraction of the animation duration).
SceneLayer items can have both a scaling factor and an animation set.
However the game seems only to support uniform (x=y) scaling in conjuction with animations, and if presented with non-uniform scaling, will use the larger scaling factor on both axes.
So scale=2,2 or 0.5,0.5 appear as expected, but scale=0.5,2 will appear in the game as if you entered scale=2,2