First, it is dark, meaning that it is not in the form of stars and planets that we see. Observations show that there is far too little visible matter in the Universe to make up the 27% required by the observations. Second, it is not in the form of dark clouds of normal matter, matter made up of particles called baryons.
Livestock[edit] The raising of livestock, sheep (the traditional mainstay for generations of Icelandic farmers) and cattle (the latter grew rapidly in the 20th century), is the main occupation, but pigs and poultry are also reared; Iceland is self-sufficient in the production of meat, dairy products and eggs.
One of Europe's most famous extinct animals, the aurochs or urus (Bos primigenius) were a very large type of cattle. Aurochs evolved in India some two million years ago, migrated into the Middle East and further into Asia, and reached Europe about 250,000 years ago.