Matsya Purana — Rite and Layout for Consecrating Ponds
षोडशारं ततश्चक्रं पद्मगर्भं चतुर्मुखम् चतुरस्रं च परितो वृत्तं मध्ये सुशोभनम् //
ṣoḍaśāraṃ tataścakraṃ padmagarbhaṃ caturmukham caturasraṃ ca parito vṛttaṃ madhye suśobhanam //
Then one should draw a sixteen-spoked wheel, with a lotus at its core and four faces (or four openings). Around it there should be a square enclosure, and in the middle a well-adorned circular form.
This verse is not about Pralaya; it belongs to the Matsya Purana’s Vastuvidya material, prescribing a sacred geometric layout (chakra–padma) used for ritual/architectural planning.
It supports dharmic duties indirectly: kings and householders were expected to commission or build sanctified spaces correctly; the prescribed mandala ensures orderly, auspicious construction aligned to the four directions.
It specifies a precise mandala/yantra plan—sixteen spokes, lotus-centered, four-directional (caturmukha), with a surrounding square and a central circular feature—used as a blueprint for temple/altar layouts and consecration-oriented design.