These fossils date back more than 345 million years to the Devonian and Silurian periods of the Paleozoic Era. Corals and brachiopods both generally live in shallow marine waters. In addition, corals are typical residents of warm seas. These fossils tell us that New Hampshire was underwater more than 340 million years ago. The climate was probably tropical, similar to places today near the equator, or subtropical, similar to Florida.
Brachiopods are among the oldest known fossils.
They are mollusks, related to such diverse animals as snails and octopuses. Unlike snails, however, brachiopods have two shells. They are called bivalves , just as bicycles have two wheels and biplanes two wings. Clams, mussels, and oysters are also bivalves. But brachiopods have a different type of symmetry , or balance, than do clams.