CORALS –(zoantharia) are chidarians that have discarded the free swimming stage
and live as attached polyps, either singly or in colonies.
They are common fossils due to their mineralised, often elaborate skeletons, which
generally resemble a curp surrounding the anemone-like creature.
Coral reefs have occurred fro much of the last 500 million years and are useful indicators or
markers for dating rocks.
The turbulent and rugose (“wrinkly”) corals did not survive the major end of Permian
mass extinction event.
All post-triassic corals, including living types, are known as scleractinians. They
superficially resemble rugose corals but they can be distinguished by their
internal ribs or septa, which are always arranged in multiples of six.
This coral is not taken live from oceans, but can be 20 million
years old and some are mined in mountain tops, especially in Indonesia and is
also known as Agatized coral.
These corals can vary greatly in colour due to mineral oxidation
from soft pastel ivory to dark browns and even whites to black colours.
The distinct coral pattern is more important than the colour
of the fossil as the patterns can be small and delicate and some to large
shapes and skeletal-like ancient coral patterns, most often appearing in single
Coral fossil from Indonesia has reputation as the best
pattern. These fossils were forced up into mountains millions of years ago in
Coral horn from Morocco are from the Zaphrentoides period
over 350 million years ago and formed in limestone deposits.
Australia has them in the great barrier reef which is
protected, and Museums do have spectacular fossil corals. But you are not
allowed to pick up coral even if you find it washed up on the beach.
Coral fossil specimens are popular in Asia especially red
coral that is natural colour. Most red coral sold today is dyed from bamboo
plant and the plant may be a fossil but is easy to find and dye red colour.
Ancient coral fossils were used as building material and for
calcium, potassium, magnesium and sodium content as health food additives.
Even volcanic ash has been found in some fossils.
Permineralization is replacement of or filling of spaces in the coral with
minerals before processed into agate rocks.