(( Note: I don't collect them, =_= trying to get annoying thoughts out of my head. ))

1.) There might be a gem of some kind with in them.
2.) A museum might pay you to display them for no appearent reason.
3.) They are great for throwing at people!
-Chuck them at neighbors!
-Throw them at the paper boy / mail man!
-KO innocent yet pesky insects with your amazing throw!
-Keep those kids off your lawn using massive boulders!
4.) Solid paper weights.
5.) They make easy-to-take-care-of pets!
6.) Create a gorgeous rock garden with the shiney ones.
7.) Watch them for an hour to get a glimpse of what early life was like.
8.) Displays primitive lifestyle.
9.) Qualifies for being a hobby.
10.) Are a great excuse for buying a catapult.