As the seafloor moves slowly east, it slides under the North American continent and leaves behind scrapings of radiolarian chert and pillow basalt. (parksconservancy.org)
They compared isotope measurements on the silica skeletons of diatoms, which store environmental signals from the ocean's surface, with isotope signals from radiolarians, which live in deeper water layers. (sciencedaily.com)
At left, a large Thalassicolanucleata radiolarian with a central capsule enclosing the nucleus. (discovermagazine.com)