bacterium (pl. bacteria)
—A tiny, one-celled living
thing that reproduces by dividing in half.
body fossil
—The hardened remains of a plant, animal,
or other creature that was once alive.
coprolite
—Fossilized animal dung.
crust
—The outer layer of Earth.
crystal
—A natural solid material made of atoms and
molecules arranged in a repeating pattern.
erode
—To slowly wear away rock or other materials by
the action of wind, water, or ice.
gem
—A beautiful crystal that has been cut and polished.
humus
—The rotting material in soil.
igneous rock
—A kind of rock that forms when magma
cools and hardens.
lava
—Magma that spills out onto Earth’s surface.
magma
—Hot, soft rock found below Earth’s surface.
mantle
—The layer of Earth between the crust and
outer core. It is made of soft rock called magma.
Words to Know
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