I would say almost all types of muscles. Skeletal, cardiac, or smooth, they all need neurons. Without them, it could cause flaccid and spastic paralysis, or other types of diseases.
Commonly called the enterics due to the fact that they inhabit the intestinal tracts of humans and other animals.
Answer:
some plants have thorns some animals have spikes
Explanation:
Yes, this is true, and it is actually one of the organisms driving evolution! Some organisms develop mutations that are actually beneficial (better eye-sight, for example) and they're more likely to pass those to their children that individuals without those mutations!