It is of the nature of the indefinable, beginningless avidyā and made of impure sattva (one of the three qualities of māyā), mixed with tamas (subtle matter).
The causal body continues to exist even after pralaya (the death of the physical body)—except in the case of the death of the gross body of a jñānī who has definitively recognized its identity as consciousness.
The end of ignorance, with the death of the gross body, is also the end of the subtle body (sūkṣma śarīra) and the causal body. Then nothing will manifest anymore.
The individual causal body is nothing other than māyā, operating at the individual level. As such, it is the individual cause of ignorance about one’s true nature and the seed or undifferentiated cause of the individual’s subtle and gross bodies.
Māyā, we might say the causal body on the cosmic or universal level, is, among other things, the storehouse of all karma, in the form of unmanifested intelligence and power. While māyā, operating on the individual causal level, because it is ignorance, is the root of individual tendencies, impressions (vāsanās), prejudices, and attitudes.
The entire complex of these within an individual is called saṁskāra. These impressions have a determining effect on the intellect, in which an assessment is made of whether and how to think, feel, and act. Because of this ignorance, the objects superimposed (adhyāropa) are mistaken for real (adyāsa).
Thus, the individual causal body is the storehouse of all individual karma (sañcita-karma). From this, a portion is activated in a human life, called prārabdha karma.
Finally, kāraṇa śarīra is also associated with the ānandamaya kośa. Its characteristic is that subject and object coincide, which allows the individual to experience reflected consciousness as bliss (bliss).
When desire is extinguished because an individual has obtained the desired object, this bliss is briefly revealed and experienced.
In deep sleep (suṣupti), the mind (buddhi, manas, citta, and ahaṅkāra) is demanifested.
The other two bodies are the gross body (sthūla-śarīram) and the subtle body (sūkṣma-śarīram).
When consciousness is identified with these three bodies it is called a jīva.