This is a life force. It is "the" life force of the body (sometimes called the sex force or reproductive force). In eastern teachings, the Kundalini is likened to the image of a serpent coiled up below the base of the spine. As this special force is released or awakened, it surges up through the different "Charkas" and makes a person aware of esoteric things. It awakens clairvoyance, telepathy, and psychometry, and enables one to live between two worlds. THE KUNDALINI IS A DANGEROUS THING INDEED, and one should not try to awaken that Kundalini without absolutely adequate supervision from an adept. You cannot do it by reading a book! If you meddle about and awaken your Kundalini the wrong way, it can lead to madness. It is one of the most dangerous things in this world to try to raise the Kundalini without knowing what you are doing. The Kundalini force actually start midway between the organ of generation and the organ of excretion. Now, the Bible story of Adam and Eve, complete with serpent and apple, is merely the story of Eve having her Kundalini awakened. And the stimulation of the nervous system and its pleasures or fruit, the "apple." This causes the consciousness which is normally inward and centered in the brain as the "witness" to leave its center and become uncentered or involved with the outer body and senses and pleasures of their stimulation. This leaving one's center is a mistake, an error, bad judgment – or sin (to miss the mark), i.e., to miss the point and not to understand how to live in the physical realm.
-T. Lobsang Rampa
Living IN the physical body is very different from living AS the physical body.
The Kundalini was also referred to as the serpent and or worm in ancient text. If incorrectly understood and misused, the Kundalini, serpent or worm can be an agent of destruction. The worm (sex force) leads to the spiritual death (not Physical) and the downfall of human beings.
-Isaiah 66:24 and Mark 9:48
Their worm does not die, and the fire is not quenched. i.e., The reproductive force is not converted into spiritual consciousness (internal alchemy); therefore the sex sensation (fire) is never satisfied.
And as Moses lifted up the serpent in the wilderness (raised the Kundalini during meditation) even so must the son of man be lifted up. (The physical consciousness lifted, actually returned to, the spiritual state.
The Kundalini is sometime referred to as the worm, because it is very small in size.