Serpent

From Oddwinds

Serpents may seem odd today, but they were they mainstay basses of the "brass" instruments for many decades up into the early 1800s. Given their rarity today, and their generally strange appearance and acoustics, they might be considered near-odd.

[edit] Odd Serpents (Category 3)

Paul Schmidt has made a plywood serpent with a square cross section; he calls it a "squarpent". If that's not odd enough, he's also made a contrabass squarpent. In addition there's a plywood ophicleide ("box-o-cleide").