Membrane of the cell/ cell wall and membrane if it is plant
<span>This phylum exists exclusively in the sea, and cannot be found on land or in fresh water.
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These fossils are very useful for us because we can use them to date the layers of rock that they are found in. Fossils that can be used in this way are called index fossils, and rock layers with the same index fossils in them can be correlated. Not my answer, link here for full
http://peter-mulroy.squarespace.com/correlating-rock-layers/
The answer is B
A keystone predator would increase niche diversity and help reduce niche competition <span />
