It is called Commensalism.
The shark is neither harmed or benefited but the remoras get the benefit of this relationship without harming the shark.
Examples of chemical mutagens would be nicotine and other compounds in cigarette smoke that cause mutations involved in lung cancer.
The rabbit population may decline if the plant life starts to die or there’s an increase in the fox or wolf population.
Hydroxyapatite is the major component of bone that contributes to its hardness.
