In this 25th anniversary retrospective on Nirvana's 'In Utero' album, drummer Dave Grohl discusses the band's creative process and confirms Cobain's interest in ancient history during the album's creation. Grohl specifically mentions Cobain's fascination with extinct plants and their cultural significance, stating: 'Kurt was always bringing these obscure historical references into his writing. He had been reading about this ancient plant that the Romans harvested to extinction... it had these heart-shaped seeds that he was really into.'