Matsya Purana — The Rohiṇī–Candraśayana Vow
श्वेतामथ सुवर्णास्यां खुरै रौप्यैः समन्विताम् सवस्त्रभाजनां धेनुं तथा शङ्खं च शोभनम् //
śvetāmatha suvarṇāsyāṃ khurai raupyaiḥ samanvitām savastrabhājanāṃ dhenuṃ tathā śaṅkhaṃ ca śobhanam //
Then one should offer a white cow, with a golden face and hooves adorned with silver, together with cloth and a suitable vessel; and also a beautiful conch-shell (śaṅkha).
This verse does not address pralaya directly; it focuses on dharma through ritual charity (dāna), prescribing auspicious forms of gifts to generate merit.
It reflects the householder/royal duty of dāna: donating a properly adorned cow and auspicious objects (like a conch) as part of ethical living, ritual responsibility, and accruing puṇya.
The significance is ritual: specifying purity and auspicious materials (white cow, gold, silver, cloth, vessel, conch) that are suitable for formal donations and sacrificial/temple-related observances.