Seriously... Now seeing what it actually is... stunning!

I’ve never seen another. Usually lives in my safe.

The snail is for calculating a pulse when using the chrono. I believe you count 20 beats, kill the chrono and then read the pulse per minute

...five years before they moved into their storied digs on the Rue de la Chapelle in Les Ponts-de-Martel. That building was pictured in Universal literature with Universal where it (even now) actually says Martel. (Pics not uploading for me, but Streetview in Google shows it.) Maybe the young Vermot, the man who four decades later saved the Zenith El Primero (and very likely Montres Zenith) from extinction, assisted the Pellaton brothers in creating what is most widely known and revered as the U