Dexivine

Dexivines are a species of plant-like creatures in the Zelda series. They are usually purplish tentacles that usually drain Link from his magic.

The Wind Waker
In The Legend of Zelda: The Wind Waker, they are found in the Forbidden Woods and inside of the Wind Temple. They remain hidden under the ground until Link approaches, they will then try to grab onto him and drain his magic. They can be easily destroyed by a single sword swing but they will grow back in a matter of seconds, which means that the best way to deal with them is just to avoid the areas where they are found.