圣母军
In 1971, Fierro played saxophone and flute on "Hooteroll?", an instrumental, free-form album by guitarist Jerry Garcia and keyboard player Howard Wales. Three years later he joined another project by Garcia known as Legion of Mary. Like Garcia's Grateful Dead, Legion of Mary combined rock and blues with long improvisation. He appeared on the Dead's album "Wake of the Flood" in 1973 and toured with them that year.