Answer:
Certain fossils, called index fossils, help geologists match rock layers. To be useful as an index fossil, a fossil must be widely distributed and represent a type of organism that existed for a brief time period. Index fossils are useful because they tell the relative ages of the rock layers in which they occur.
Answer:
6. antibodies and DNA for the question no.6
Mechanoreceptors respond to mechanical stimuli that result from physical interaction, including pressure and vibration
I believe it's sexual reproduction in sea stars if that's the question.
<span />
