Swamolas are enemies that have appeared in The Legend of Zelda: A Link to the Past.
A Link to the PastSwamp of Evil in the Dark World. The Swamp is the counterpart to the Desert of Mystery from the Light World.
Swamola are swamp worms that have larger pincers at the top of their heads. They will pop up from the water and will glide through the air for a few moments before then diving back underwater. Their actions are very similar to their larger Lanmola cousins, who served as the dungeon boss in the Desert Palace.
Their heads and pincers bear a resemblance to the Devalant that are encountered within the Desert Palace. However, Devalant never leave the sandy grounds where they live, so it's unclear whether these were intended to be the same enemies.
Swamola are very strong enemies, doing four full hearts of damage if they come into contact with Link. However at the time Link encounters Swamola, he likely has the Blue Mail, which reduces the damage taken to three hearts. With the standard Master Sword, it will take four sword slashes to defeat these creatures.