sedimentary (chemical), Mn/Fe oxide crusts and nodules
Thin white outline surrounding rock where broken, broken sides are very thin, came from rock folded like a ribbon, dead coral?
Cite the IMLGS database as: Curators of Marine and Lacustrine Geological Samples Consortium. The Index to Marine and Lacustrine Geological Samples (IMLGS). National Geophysical Data Center, NOAA. doi:10.7289/V5H41PB8 [date of access].