Short For 
It Contains Genes
If this is true, than the animal that is embedded in this fossil most likely would have had opposable thumbs, which are crucial for using tools and climbing trees.
Answer:
it adapts , it starts to create an imunity against anitbodies
(I'm not sure if i am right )
They decrease because the zebra mussel were taking their resources. Leaving them nothing to eat.
Reptiles are ectotherms and cannot raise their body temperature above that of the environment.
