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coral

(Encyclopedia)coral, small, sedentary marine animal, related to the sea anemone but characterized by a skeleton of horny or calcareous material. The skeleton itself is also called coral. Although most corals form c...

clam

(Encyclopedia)clam, common name for certain bivalve mollusks, especially for marine species that live buried in mud or sand and have valves (the two pieces of the shell) of equal size. The oval valves, which cover ...

fossil

(Encyclopedia)fossil, remains or imprints of plants or animals preserved from prehistoric times by the operation of natural conditions. Fossils are found in sedimentary rock, asphalt deposits, and coal and sometime...

fluorine

(Encyclopedia)fluorine flo͞oˈərēn, –rĭn [key], gaseous chemical element; symbol F; at. no. 9; at. wt. 18.9984; m.p. −219.6℃; b.p. −188.14℃; density 1.696 grams per liter at STP; valence −1. Fluorin...

Jurassic period

(Encyclopedia)Jurassic period jərăsˈĭk [key] [from the Jura Mts.], second period of the Mesozoic era of geologic time, lasting from 213 to 144 million years ago. At the start of the Jurassic most of the contine...

lake, body of water

(Encyclopedia)lake, inland body of standing water occupying a hollow in the earth's surface. The study of lakes and other freshwater basins is known as limnology. Lakes are of particular importance since they act a...

space science

(Encyclopedia)space science, body of scientific knowledge as it relates to space exploration; it is sometimes also called astronautics. Space science draws on the conventional sciences of physics, chemistry, biolog...

explosive

(Encyclopedia)explosive, substance that undergoes decomposition or combustion with great rapidity, evolving much heat and producing a large volume of gas. The reaction products fill a much greater volume than that ...

fats and oils

(Encyclopedia)fats and oils, group of organic substances that form an important part of the diet and also are useful in many industries. The fats are usually solid, the oils generally liquid at ordinary room temper...

gold

(Encyclopedia)gold, metallic chemical element; symbol Au [Lat. aurum=shining dawn]; at. no. 79; at. wt. 196.96657; m.p. 1,064.43℃; b.p. 2,808℃; sp. gr. 19.32 at 20℃; valence +1 or +3. Gold is very ductile and...