Most coral species are listed under CITES Appendix II, so importers must present a valid CITES export permit from the country of origin and a US import permit issued by the Fish & Wildlife Service. Failure to produce these documents can result in seizure at the port of entry.

Yes — heading 0508 explicitly includes powder and waste of the covered materials, so crushed shell, shell grit, and cuttlebone fragments all fall here provided the material has not been cut to shape or further manufactured into articles.