The three different forms of Mahā-viṣṇu—namely Kāraṇodakaśāyī Viṣṇu, Garbhodakaśāyī Viṣṇu and Kṣīrodakaśāyī Viṣṇu, who are the origin of creation and maintenance—are gradually being described. From Mahā-viṣṇu, Garbhodakaśāyī Viṣṇu is generated, and from Garbhodakaśāyī Viṣṇu, Kṣīrodakaśāyī Viṣṇu gradually expands.
SB 7.9.33, Translation and Purport: This cosmic manifestation, the material world, is also Your body. This total lump of matter is agitated by Your potent energy known as kāla-śakti, and thus the three modes of material nature are manifested. You awaken from the bed of Śeṣa, Ananta, and from Your navel a small transcendental seed is generated. It is from this seed that the lotus flower of the gigantic universe is manifested, exactly as a banyan tree grows from a small seed.