Answer:
Explanation:
The first mass extinction is called the Ordovician-Silurian Extinction. It occurred about 440 million years ago, at the end of the period that paleontologists and geologists call the Ordovician, and followed by the start of the Silurian period. In this extinction event, many small organisms of the sea became extinct.
They find shells that other crabs have left behind and use them
I would go with c because its tells you right in there that the ecosystem help who lives around that area.
Have cones as reproductive structures.
Have vascular tissue.
