Gigas giant clam

The Gigas Giant Clam is a sea creature in introduced in the 1.3.0 Free Summer Update. Its shadow is large and it swims away very fast.

In
When donating to the museum, Blathers will say the following:

"Gigas giant clams live in warm-water coral reefs and are the biggest bivalves in the world. Growing as wide as six feet and weighing up to 600 pounds, these clams can live to be 100 years old. And yes, these mighty creatures look as though they could eat a swimmer whole. But they eat plankton instead and get valuable nutrients from an algae they live in symbiosis with. Indeed, these enormous gents get all the sustenance they need by lying face up with their shells half-open. If such was my life, I'd be happy as a clam too."