Plankton Wat is the solo project of Dewey Mahood, a prolific experimental musician based in Portland, Oregon, who's been in countless bands since the late '80s, and is perhaps best known as the guitarist for heavy psych jammers Eternal Tapestry. His recordings as Plankton Wat have drifted between earthy, acoustic psych-folk and effects-heavy cosmic stoner rock, occasionally featuring vocals or electronic textures. The project released several cassettes and CD-Rs throughout the 2000s, mostly recorded by Mahood at home, making its vinyl debut at the end of the decade with Dawn of the Golden Eternity. Subsequent albums for labels like Thrill Jockey, including 2012's Spirits and 2021's Future Times, have been more collaborative and boast a more fully developed sound.

Mahood began playing the bass in punk bands in Chico, California, in the 1980s, initially for the hardcore group Empty Offer in 1987. He soon switched to guitar, playing in psychedelic, grunge, and free improv bands. He briefly lived in Seattle at the end of the '80s, and he settled in Portland in 1992, where he formed the post-punk band Elephant Factory with Larry Crane of Tape Op magazine. He formed the free jazz-influenced Cosmos Group in 2000, then started his solo home recording project Plankton Wat, named in tribute to Krautrock producer Conny Plank and bassist Mike Watt, in 2001. The project debuted in 2002 with a handmade CD-R titled Interstellar Sounds Of. Mahood then spent a few years playing as part of the avant-rock trio Scuffle Dustcough, then co-founded Eternal Tapestry in 2005, touring frequently and releasing acclaimed albums on labels like Not Not Fun and Three Lobed Recordings. He remained active as Plankton Wat, resuming the project with the 2007 CD-R Other Worlds (self-issued on his own Solar Commune imprint), followed by several cassettes and CD-Rs on well-regarded underground labels like Digitalis Limited, Blackest Rainbow, and Stunned Records. DNT Records released Plankton Wat's first LP, Dawn of the Golden Eternity, in 2009. Additional limited releases followed on labels like Sloow Tapes and Reverb Worship, and Mahood participated in other projects like Gärden Söund (with members of Barn Owl) and dub-funk group Edibles.

Eternal Tapestry signed to Chicago's Thrill Jockey in 2011, and Plankton Wat's first album for the label, Spirits, appeared in 2012. The single-sided 12" EP Mirror Lake was released by Sound of Cobra later in the year, and Plankton Wat shared a 2013 split LP with Expo '70 on Debacle Records, which arrived around the same time as second Thrill Jockey full-length Drifter's Temple. Mahood formed Spectrum Control with Dustin Dybvig (Horse Feathers, Edibles) and Galaxy Research with James Shaver (Million Brazilians, Deep Earth). Plankton Wat returned in late 2017 with Hidden Path, issued by Sky Lantern Records, which featured post-production and additional instrumentation by Dustin Dybvig, as well as flute by Ash Dybvig, bass by John Rau, and lap steel guitar by Matt McDowell. The Healing Earth, entirely improvised and home-recorded by Mahood, was digitally released for Earth Day in April 2019. Plankton Wat's third Thrill Jockey release, Future Times, appeared in 2021. Co-created with Dustin Dybvig and engineer/producer Victor Nash, the album reflected on social unrest as well as climate change. Thrill Jockey gave Hidden Path a wider release in 2022. ~ Paul Simpson, Rovi