Answer:
Endoskeleton
Explanation:
An internal skeleton is called an endoskeleton, which is what vertebrates have. A sponge endoskeleton consists of short, sharp rods called spicules
Spicules are made of silica, calcium carbonate, etc.
C, pretty sure due to natural selection and theory of evolution
The origin of life<span> on Earth is a set of paradoxes. In order for </span>life<span> to have gotten started, there must have been a genetic molecule something like DNA or RNA capable of passing along blueprints for making proteins, the work horse molecules of </span>life<span>.</span>
Answer:
involve calcium voltage-gated channels
Explanation: