Garden Hedgehog .:SHD:.

This 2-prim sculpted hedgehog moves randomly in a 10m x 10m
square area. It is easy to set up: just rez, position it in the center
of the area you want it to move in, and touch it — the little urchin will
record its starting point and start moving. To change the hedgehog’s
area, touch it to stop it, move it to its new center point and touch
again to restart.

The hedgehog is copiable, so if one gets lost, just rez a new one.
Or you could have a whole bunch of hedgehogs!

The hedgehog is non-physical and will move through objects. It cannot
(currently) follow Linden ground, so it is best to let it run only on
flat or almost-flat areas.