Before joining Metallica in 2003, Robert Trujillo was a member of which band?

Roberto Agustin Trujillo (Spanish pronunciation: [roˈβerto tɾuˈxiʎo]; born October 23, 1964) is an American musician and songwriter best known as the current bassist of the heavy metal band Metallica, a position he has held since 2003. He was also a member of crossover thrash metal band Suicidal Tendencies, funk metal supergroup Infectious Grooves, heavy metal band Black Label Society, and has worked with Jerry Cantrell, and Ozzy Osbourne.

Suicidal Tendencies (also referred to as S.T. or simply Suicidal) are an American crossover thrash band founded in 1980 in Venice, California by vocalist Mike Muir, who is the only remaining original member of the band.

Trujillo is primarily a finger-style player, but has been known to play with a pick in some recordings and while playing live. Trujillo's predecessor in Metallica, Jason Newsted, was almost exclusively a pick-style player, while Cliff Burton, Newsted's predecessor and bassist on Metallica's first three albums, played finger-style exclusively. Trujillo is known for playing "massive chords" and "chord-based harmonics" on the bass.

Trujillo also uses the slap bass technique, seen mostly in his work with Suicidal Tendencies and especially Infectious Grooves. At many of the shows during Metallica's 2004 Madly in Anger with the World Tour, Trujillo would often play an extended bass solo (dubbed "Jungle Essence" on recordings), which made extensive use of slap bass and other techniques and effects.