Looks & Song
It is a golden-bronze ring with SpongeBob and Patrick inside it. The song goes like this:
It's the best friends forever, Best friends forever ring!
SpongeBob and Patrick were having an argument during the time of Patrick's Secret Box. Patrick made a threat to SpongeBob that if he didn't stop trying, they would no longer be friends. SpongeBob didn't listen and then forced himself to get the box, making a lot of noise. SpongeBob had to prove he was not the Clam Burglar, and show the Friendship ring, making Patrick sad and angry.