Nature - Rocks, Fossils & Shells

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A marine invertebrate of the phylum Brachiopoda, which comprises the lamp shells.

Are marine animals that have hard      "valves" or "shells" on the upper and lower surfaces.

Lifespans range from three to over thirty years.

Fossils have been useful indicators of climate changes.

Over 12,000 fossil species are recognised.

In the peak of the Paleozoic era, the      brachiopods were among the most abundant filter-feeders and reef-builders.

A marine bivalve mollusk with shells of equal size.

Informal term used to refer to any molluscans.

Live in both freshwater and marine habitats.

Some have life cycles of only one year, while at least one has been discovered that may be over 500 years old.

Clam's shell consists of two (usually equal) valves.

Clams can be eaten raw, steamed, boiled, baked or fried.

A hard solid mass formed by the local accumulation of matter, especially within the body or within a mass of sediment - also known as kettle.

Is a hard, compact mass of matter.

Are often ovoid or spherical in shape.

Form within layers of sedimentary strata.

Vary in shape, hardness and size.

Are commonly composed of a carbonate mineral.

Are found in a variety of rocks, but are particularly common in shales, siltstones, and sandstones.

"Cannonball" concretions are large      spherical concretions.

An echinoderm of the class Crinoidea, which comprises the sea lilies and feather stars.

Are marine animals.

Sea lilies refer to the crinoids which are attached to the sea bottom by a stalk.

Comprise three basic sections; the stem, the calyx, and the arms.

Majority of living crinoids are free-swimming.

A soft, finely stratified sedimentary rock that formed from consolidated mud or clay and can be split easily into fragile slabs.

Fine-grained, clastic sedimentary rock,

Characterised by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness.

Black shale can also be referred to as black metal.

Clays are the major constituent of shales.

Shales contain roughly 95 percent of the organic matter.

Process in the rock cycle which forms shale is called compaction.

Are typically deposited in very slow moving water and are often found in lakes and lagoonal deposits.

"Black shales' are dark, as a result of being especially rich in unoxidized carbon.