Soma was one of the Aṣṭavasu (Ashtavasu; the Eight Vasus) in Svāyambhuva(Swaymbhuva) Manvantara. Ūrmi (Urmi) is one of the sons of Soma.

Vāyupurāṇa(66.23)
Brahmāṇḍapurāṇa (Maharṣi)(2.3.23)