In Jainism, nigod (also written nigoda) is the lowest and most primitive form of life (jiv).

Very simple explanation:

• What is nigod?

Tiny, microscopic living beings with only one sense – touch. They live in clusters, many souls together in a common body.

• Spiritual level:

- They have very little consciousness. - They are heavily bound by karma. - They cannot do any spiritual effort in that state. - They are at the lowest step of the life ladder.

• Number of nigod:

Jain scriptures say innumerable souls remain in nigod state for an extremely long time. Only very rarely a soul comes out of nigod and slowly starts taking higher births.

• Types often mentioned:

- Nitya-nigod – souls that have always been in nigod state. - Itara-nigod – souls that were higher before, but due to karma fell back into nigod.

• Why is this important?

- It shows how many souls exist in the universe. - It shows how rare and precious a human birth is for doing dharma and going towards moksh. - It explains why Jains stress ahimsa so much – even water, soil, plants etc. are full of such tiny nigod jivs.

Both Shwetambar and Digambar accept the basic idea of nigod as the lowest one-sensed life form; there may be small differences in detailed descriptions in their texts, but the main concept is the same.

You can read more here and here