He is conducting research on natural phenomena.

It's a natural phenomenon for newborns to secrete witch's milk.

It is said that a ghost lives in that old house.

Taking care of a newborn is hard.

His body started excessive secretion in response to stress.

This plant secretes a special liquid.

This phenomenon remains unexplained for scientists.

I love nature.

Vampires suck human blood when it becomes night.

This park is very rich in nature.