Matsya Purana — Śrāddha Procedure: Types
षट् च तस्माद्धविःशेषात् पिण्डान्कृत्वा ततोदकम् दद्यादुदकपात्रैस् तु सतिलं सव्यपाणिना //
ṣaṭ ca tasmāddhaviḥśeṣāt piṇḍānkṛtvā tatodakam dadyādudakapātrais tu satilaṃ savyapāṇinā //
Then, from that remaining oblation (havis), he should prepare six piṇḍas (rice-balls). After that, he should offer water—using vessels meant for water—mixed with sesame seeds, pouring it with the left hand.
This verse does not address pralaya; it focuses on śrāddha procedure—specifically making piṇḍas from the remaining havis and offering satila (sesame-mixed) water.
It prescribes pitṛ-kārya (ancestor duties) expected of householders (and kings as exemplars): preparing piṇḍas from consecrated remnants and offering sesame-water according to ritual etiquette (including the specified hand and vessels).
The significance is ritual, not architectural: it specifies the śrāddha mechanics—six piṇḍas from havis-śeṣa and udaka-dāna using water vessels, with sesame, poured with the left hand.