No, a missing piece of Antikythera Mechanism has not been found (well, probably not)

The Antikythera wreck is a shipwreck from the 2nd quarter of the 1st century BC. It was discovered by sponge divers off Point Glyphadia on the Hellenic island of Antikythera in 1900. The wreck manifested numerous statues, coins and other artefacts dating back to the 4th century BC, as well as the severely corroded remnants of a device that is called the world's oldest known analog computer, the Antikythera mechanism.

The Antikythera mechanism is an ancient analog computer designed to predict astronomical positions and eclipses. The computer's construction has been attributed to the Hellenes and was originally dated to the early 1st century BC. Technological artefacts approaching its complexity and workmanship did not appear again until the 14th century, when mechanical astronomical clocks began to be built in Western Europe.

The mechanism was housed in a wooden box and is made up of bronze gears (that we know of). The mechanism's remains were found as eighty-two separate fragments of which only seven contain any gears or significant inscriptions. Today, the fragments of the Antikythera mechanism are kept at the National Archaeological Museum of Athens.

Since 2012, divers have been returning to Antikythera to scour the steep underwater cliff-face for more treasures. The wreck was severely damaged by explorer Jean-Jacques Cousteau in the 1970s when he hauled a multitude of marble and bronze statues from the seabed. What remains has been scattered about, or tumbled further into the deep.

Now, a new article in the Israeli publication Haaretz has sent a quiver of anticipation around the world. It declared it to be a lost cog from the Anikythera mechanism itself. And, as it carried the sign of a bull — Taurus — it proves the machine was more complex than many dared dream. The bronze disc, however, seemed promising. It had four protrusions, large ‘cog’-like teeth spaced at regular intervals. It’s since been X-rayed and scanned. The new disk, if it belonged to the device could confirm its ability to predict the position of the groups of stars so important to the priests and seers of the era.

But the bull-engraved plate is very unlikely to be part of the device’s complex workings. If the four protrusions were cogs, they’re unusually crude for such a intricate device. Most likely, they were practical attachments for whatever the disc adorned. At best, the bull-disc could have been an ornamental piece attached to the Antikythera Mechanism’s case. But it’s just as likely to have decorated some long-decayed panel of wood, or even priestly robes. Meanwhile, the hunt for more pieces of the mechanism continues.