The fire is the oldest continuous layer of the religion, and almost all of it has been folded into other rites. Every Hindu wedding is conducted around one; housewarmings, thread ceremonies and funerals all use it; and the domestic agnihotra, an offering at dawn and dusk, is kept by a small number of households. What survives most remarkably is the full shrauta tradition — the large public Vedic sacrifices requiring multiple priests, precisely built altars and days of recitation — maintained by a few hundred families, principally Nambudiri brahmins in Kerala and some lineages in Andhra and Maharashtra. The Athirathram, a twelve-day soma ritual with a bird-shaped altar of a thousand and some bricks, has been performed a handful of times in living memory and was filmed in 1975 by Frits Staal, whose documentation is the reason it is known at all. Animal offerings in these rites were largely replaced by rice-flour substitutes centuries ago, a substitution the texts themselves record.