Laser Clam Clamp

The Laser Clam Clamp is only found in a certain part of Blue Battle Bay. It Is blocking the Sea Shelter. You find Swimmuscle Pikmin nearby but there is no onion! and you only get 5 of them. You can't bring them into dungeons, and once you enter the dungeon the Swimmuscle pikmin are gone. 5 is enough to complete the puzzle and get to the dungeon.

Clam Puzzle
This is the only time that these "enemies" are found. You must throw the Swimmuscle pikmin onto different clam clamps to stop the lasers. However, when the pikmin are taken off, the lasers come back. It is a fairly complex puzzle.