Answer first
Hippocampus is the seahorse emblem stamped on the caseback of Omega Seamaster watches. "Replica hippocampus 2016" is a search phrase used in the replica trade. It points to copies of Seamaster models sold around 2016. It is not a model name used by Omega. It is not a Rolex feature. No Rolex watch carries a hippocampus mark.
Where the term comes from
Omega has used the seahorse on Seamaster casebacks since the 1950s. The mark appears on Seamaster 300, Planet Ocean, and Aqua Terra models. In 2016 the Seamaster Planet Ocean line carried the Master Chronometer label. Case sizes were 39.5 mm, 43.5 mm, and 45.5 mm. Steel Planet Ocean references begin with 215.30.
What sellers list under this label
Listings group three product types under the phrase:
- Planet Ocean 600M copies with a display caseback and a decorated rotor.
- Seamaster 300 copies with a closed caseback and an engraved seahorse.
- Aqua Terra copies with a teak pattern dial.
Most of these run an Asian copy of an ETA 2824 or a decorated clone of the Omega 8500. Decoration plates do not change the base movement.
Points to check
Caseback engraving depth. Crown etching. Bezel insert lettering. Date window position at 3 or 6. Lug width in millimeters. Weight in grams. A 43.5 mm steel Planet Ocean weighs about 100 g on a rubber strap and about 200 g on a bracelet. Copies fall outside those numbers.
Legal status in the US
Import and sale of counterfeit watches is illegal in the United States. 18 U.S.C. 2320 covers trafficking in counterfeit goods. CBP can seize shipments at ports of entry. Omega does not service or authenticate watches it did not make. A buyer has no warranty path.
What is not known
No public data separates 2016 output from other years at the factories that produce copies. Claims about a single source factory or a 1:1 grade are seller claims. They are not measurable specs.