I found this in Topanga Canyon, California (LOS ANGELES). It can be scratched with a penny, but not my fingernail: hardness is about a 2.75 I guess. The size of a baseball.
I found this on the edge of a field on a mountain ranch within the Santa Monica Mountains. We are 5 miles north of the Pacific Ocean.
Thank you JulPal! I’ve been looking at concretion pics for months... just never saw anything similar. Yes, this item is round, but I’m puzzled by the white fibrous outer ‘shell’ as well as the embryonic interior and crystallized center.