This is a vintage Omega bumper automatic movement, specifically from the Caliber 350 series (such as Cal. 351, 354, etc.), housed in a case featuring the iconic Omega Constellation "Observatory" case back medallion—though the medallion shows significant wear.
Movement Brand: Omega (Switzerland)
Movement Type: Bumper Automatic / Hammer Automatic (The winding rotor pivots back and forth between two spring-loaded bumper blocks rather than rotating a full 360°).
Caliber Group: Omega Caliber 350 series (likely 17 Jewels, copper-finished/gilt plates).
Case Serial Number: 434507 (Stamped clearly between the lugs at the 6 o'clock position).
Case Back Emblem: Features the historical Omega "Observatory under the stars" crest with the text "SINCE 1848".
Missing Components: CRITICAL — The entire automatic winding bridge and bumper rotor assembly are missing. The movement is currently reduced to its manual-winding base.
Crown & Stem: The crown and winding stem are missing. Only the empty crown tube remains on the side of the case.
Jewels & Train: Red ruby jewels are intact on the visible wheel bridge and balance cock.
Current Operational Status: Untested. Given the missing auto-wind mechanism and crown, this movement should strictly be considered "For Parts or Repair."
Dial Condition: Heavily oxidized, discolored, and degraded. The original branding, text, and minute tracks have been completely worn away.
Markers: The faceted, arrow-head hour markers and the date window frame (at 3 o'clock) remain attached to the dial plate but show surface aging.
Hands: Completely missing.
Crystal: Domed acrylic crystal is present but shows deep scratches and scuffs around the edges.
Material: Base metal or stainless steel case (heavy scratching and scuffs throughout the lugs and bezel).
Lugs: Standard drilled lugs, showing heavy wear and tool marks.
Case Back Medallion: The gold-toned observatory insert is heavily worn, tarnished, and has lost a significant amount of its original detail due to past friction or corrosive wear.
Inner Case Back: Features a clean, tight perlage (circular graining) pattern finish.