opossums do not have quills. You are thinking of the porcupine.
Porcupines have quills.
These are called quills. They come loose and get stuck in the skin of animals that they come in contact with.
a porcupine has quills
I think it serves as they're protection against predators.
Only animals that are larger than it that try to eat them. However, its quills protect it.
A porcupine has quills to defend themselves against harm's way (defend them from predators).
An adaptation of the porcupine is their sharp claws, which they use to tear off parts of trees to eat. They also have quills, in order to protect themselves.
it has about 30,000 quills
the porcupine is born with its quills a@#$@#*.
Porcupines have quills which look like needles on their backs. These protect the porcupine against predators and come contain a poison.
Porcupine quills can range from 6 cm to over 20 cm in thickness.