The correct answer is chitin. This glucose derivative is in
fact the main building block of cell walls in not only arthropods (including
the shrimp), but also fungi and insects, and also has a structural function in
the scales of fish. The most similar commonly-known substance in terms of
function is keratin, which makes up our hair and nails.
Answer:
C. 444 Ma
Explanation:
The first plants that managed to colonize the land appeared around 470 million years ago, while the first arthropods on land appear i the fossil records around 450 million years ago, so we can say that around the period of 444 million years ago they were well established on land. The first arthropods that started to have terrestrial life were almost identical to those in water, with only minor changes that enabled them to breathe and move more easily. The first plants on land were non-vascular plants. They were small as they initially didn't had deep and well established roots.
Slate starts out as shale under the surface of the Earth before its metamorphosis. It is typically gray in color and splits along long flat planes. It is also does not allow water or other liquids to pass through it. Slate is most often used as a roofing material, decorative gardening stone and a base for snooker tables. In the Victorian era, it was commonly used as a writing board.
Marble is another one of the metamorphic rocks and is a metamorphosed limestone. It has a hard crystalline rock appearance and was the stone of choice in ancient Greece. In fact, more than 22,000 tonnes of marble were used to build the ancient Greek Parthenon and marble remains a popular building and sculpture material today. It can also be ground down to make cleaning products or soaps.
Schist is another metamorphic rock that is formed from either mud or shale. However, it is formed at a much higher temperature than slate is. Schist is a fairly weak rock so it does not make for a good building material. It is used for paving and occasionally sculpture.
It would mean that the organisms rely on each other for survival.
Hope this helps (:
