Strange rocks obtained by training Woodcutting are part of the Dahmaroc statue. Two Strange rocks from each skill are required to complete the statue, which can be built once per week. Strange rocks may be stored inside a statue collection bag.
Cutting any wood, ivy, Jadinko Lair roots, or jungle near Tai Bwo Wannai as well as training at the sawmill. It is recommended to chop ivy or crystal trees, since banking logs is not needed. Skillchompas will work.
It does not matter what you cut. You have a chance to get a rock every animation.