Atlantean amulet
The Atlantean Amulet is a golden piece that was broken in half. The first piece was displayed in a museum of Bikini Bottom. In the episode Atlantis SquarePantis, the second half SpongeBob and Patrick found in a cave. It was soon put together, and it presented a van to Atlantis.
Looks
It looks like a golden piece that belonged to Atlantis. It has a big A in the middle. It had a great sparkle coming out of it and it was presumably made of gold.
"Death"
The Amulet was taken off the Vantis by Lord Royal Highness, and then thrown into a dumpster.