Evolution What the Fossils Say and Why it Matters

FIGURE 8.1. A typical assortment of planktonic microfossils from a deep-sea core. Each is about the size of
a pinhead or smaller, and many thousands are found in every cubic meter of sediment. They include the
foraminifera (larger bubble-shaped shells) and the radiolaria (smaller porous conical shells), along with long,
spikelike sponge spicules. (Photo courtesy Scripps Institution of Oceanography)