Aside from being edible, oysters are most well-known for the fact that they produce beautiful, valuable pearls. In fiction, however, their ability to do this is often exaggerated — for example, it usually takes much less time for a fictional oyster to create a pearl than it does in real life. And it's not just oysters that can do it — any bivalve can create pearls, though clams are most commonly used.
Although most fictional pearls are round and perfect naturally, the process of making them look like that in real life is far more complex. It's a delicate procedure that takes place at special "pearl farms".
Also, fiction tends to gloss over why bivalves have pearls. In real life, it happens when an irritant, like a small stone, gets into the oyster's body. The oyster covers the irritant with a special substance called nacre (aka "mother of pearl") to protect the oyster's body. The nacre eventually forms and hardens into a pearl. In pearl farms, workers perform surgery to plant particles in the oysters' bodies to get them to make pearls. But in fiction, bivalves just suddenly make pearls, often for seemingly no other reason than to display them, or for a character to take them.
- In Jimmy Neutron: Boy Genius, Jimmy made pearl necklaces from actual pearls on oysters in order to impress his mom to allow him to go to Retroland tonight. He actually put sand on each oysters and microwave them that somehow accelerate their growth by heating them to 4 years.
- In one scene of Finding Dory, Dory and Hank meet a loudmouthed clam who speaks by moving his shell like a mouth. He has a fairly big pearl, seen rolling around in his shell whenever he opens his mouth.
- 20,000 Leagues Under the Sea: One of the undersea sights Nemo gives Arronax is an astoundingly huge pearl in a giant oyster. Arronax suspects the pearl was caused by Nemo putting a grain of sand inside the oyster.
- One short story by Bernard Werber has a massive space rock crash into Paris. The most remarkable thing about it is that it stinks, causing the city to desperately look for a way to handle it. Eventually someone hits on the idea of encasing it in layers of concrete and glass, which not only stops the smell but actually looks very pretty. Then an alien jeweler removes the iridescent rock from Earth and presents it to his customer, both huge enough to use the thing as, well, jewelry.
- Club Penguin: In "Aqua Grabber", there is a giant clam with a pearl. The player can steal the pearl by performing a Weight and Switch with a rock.
- Clams appear in Bricks Of Atlantis, in which hitting them will the ball will open them, each times revealing a pearl worth many points.
- Discussed in Colossal Cave. You find a "giant clam" in one room. Once you pry it open:
A glistening pearl falls out of the clam and rolls away. Goodness, this must really be an oyster. (I never was very good at identifying bivalves.)
- The Clambo enemy in Donkey Kong Country and Donkey Kong Land attacks by spitting out pearls, often more than one at a time. In the latter game, there is a King Mook called Colossal Clambo, whom the player defeats by getting its pearls to bounce back at it.
- In Feeding Frenzy, the clam at the bottom of the screen occasionally opens to reveal a pearl that can be stolen for bonus points.
- Niko the oyster from Insaniquarium creates a pearl every few minutes. Each one yields a lot of money.
- In Pikmin, the Pearly Clam Clamp enemy guards a pearl (except for one that is guarding the Positron Generator, one of the pieces of the Dolphin, Captain Olimar's spaceship). This pearl can produce 50 Pikmin when brought back to one of the Onions, but the Pearly Clam Clamp is very protective of it, and will close its mouth over the Pikmin and eat them if they are not called back fast enough, even after they've recovered it.
- The Pokémon Clamperl resembles a giant clam, with a pink pearl for its head, resting in the shell. Cloyster, which resembles an oyster, also has what appears to be a black or purple pearl for a head.
- Clamperl is a possible subversion, as it is implied that the "pearl" is in fact a fish egg that lives inside a clamshell, seeing as how it evolves into Huntail or Gorebyss (which are similar to eels).
- Tasty Blue: Some levels feature three clams that repeatedly open and close, sometimes with a pearl, sometimes not. The player needs to eat the pearls to grow bigger, so he can eventually eat the clams himself.
- Ultimate Crab Battle: One of the crab's attacks is splitting his body in half lengthwise and opening up like a clamshell to reveal a pearl inside of him. It shoots reflected light beams at you.
- Wii Party's minigame Pearl Plunder has the Miis trying to collect pearl produced by some scallops when the latters open their shells.
- Opening a clam in World of Warcraft will sometimes yield a pearl.
- The first Freddi Fish has a trio of oysters that challenge you to a shuffling game, in which you must pick one holding a pearl that is earned as a prize. Said pearl is used to give to King Crab in exchange for a Message in a Bottle.
- Squid Ink: The oyster (which looks like a clam) produces pearls (used as the Idle Game's persistent currency) every hour, in amounts that quickly require scientific notation to quantify.
- Futurama has rare non-bivalvian example: In Bendin in the Wind, the exhaust from the antique VW minibus causes Dr. Zoidberg to cough up pearls. Probably justified by his Bizarre Alien Biology.
- Spongebob Squarepants:
- Subverted in the episode "The Smoking Peanut". Clamu the giant oyster is fond of her pearl, which she can shoot into the air as part of her performance, and it turns out that the reason she went on a rampage was that Mr. Krabs stole her pearl, which is actually an egg.
- The episode "Clam Whisperer" has SpongeBob befriending a school of clams who follow him everywhere. At one point the clams keeps shooting pearls at Mr. Krabs, to his delight (and pain).
- The 1960s Popeye cartoon "Wimpy the Moocher" plays with this. Wimpy shows up at Rough House's diner and orders an oyster with his only dime. Wimpy discovers a pearl in his oyster, and Rough House gives him 30 hamburgers for the pearl. When Rough House goes to sell the pearl, he learns that it's just one of many imitation pearls Wimpy had bought earlier—for 10 cents each.
- On the Bugs Bunny cartoon "Ali Baba Bunny", Bugs finds a pearl in one of the steam clams he's been eating. It's immediately taken by Daffy Duck, who has been shrunken down by a genie. The clam closes in on him for the Iris Out.
- According to The Other Wiki, almost any shelled mollusk can produce pearls of some kind, under the right circumstances, but most species produce unattractive pearls with no gem value. On the other hand, there are a few non-oyster species that do produce pearls of gemological interest, including certain clams, scallops, and sea-snails.