not all from my rays either... friends rays, LFS and salt rays... i had a large collection...only kept a few and they are up with my jewler in the city..
Ive got a few, the smallest from a motoro around 8-9" is around 2.5" and a few biggish ones around 4-5" from a 22" Disc motoro. my marbles recently shed his but i cant find it.