Leema Mountain is the project of Sean O'Connor, known by his stage name Leema (or LIMA). Formerly a founding member of the band Lima Research Society, Leema brought his theatrical and whimsical psychedelic rock stylings to the northeast music scene. There, he played with local legends such as Lemon Demon, Uncle Monsterface, and Math The Band in the mid to late 2000s. The band Lima Research Society released their full length debut album "Don't Give Up, Don't Get Down" in 2009. The album drew influence from The Flaming Lips, MGMT and Queen, while the band's live shows drew heavy influence from the light shows and balloons-and-confetti atmosphere of a Flaming Lips concert. The band would explore themes of existentialism and outer space, with a whimsical layer of humor on top.

Leema began producing solo music under the name Leema Mountain in 2010, producing a followup to "Don't Give Up..." entitled "Brothersister."

In the years since, Leema has continued to self-produce psychedelic rock music on his Bandcamp page, with the latest effort being the 34-minute King Gizzard-inspired "Speculoosaga" - an three-part odyssey about space exploration.