The Paleolithic is the first era of human history.

This mineral is called ulexite and has special optical properties.

The Neolithic was an important period in human history.

He is known as an expert in psychoanalysis.

As the name suggests, chordates are a group of animals that have a notochord.

The spinal reflex is a part of our body that reacts automatically.

He is strong like a stone.

Do you have any questions concerning the job?

His face was filled with distress.

I picked up the trash that was lying in the park.