The Eclectic Bass is a bass guitar belonging to Jade. It can either operate as a regular bass guitar, or can be switched to a more complex setting, which renders it fully playable only if you have a few extra arms, something only managed so far by the Dreambot.
Jade leaves the guitar after Bec catches her in the Frog Temple as it was caught in the temple's elevator, and she has trouble drawing it on her Pictionary Sylladex, failing multiple times, unintentionally captchaloguing ghost images of a regular bass and Johnny 5 in the process.
It is found years in the future (but not many) by the Aimless Renegade. It appears to be blocking the elevator in the Frog Temple, and AR accurately assumes it is some kind of peculiar musical instrument that is centuries old.