• Jul 25, 2026 crinoids and blastoids exploring dinosaurs and pr d. They reached their peak diversity during the Paleozoic Era, especially in the Mississippian (Early Carboniferous) period. What Are Blastoids? Blastoids, or "sea buds," are extinct echinoderms within the class Blastoidea. They resemble crino By Ethelyn Schaden
