A Pygmy Skulltula is an enemy encountered exclusively in Twilight Princess. They are just like regular Skulltulas, except they are smaller and hang from thinner webs. Additionally, this version of the Skulltula only appears within the Forest Temple.
Link first encounters a Pygmy Skulltula inside the Forest Temple, where it drops from the ceiling when he attempts to jump over a small gap. With it there, Link cannot cross the gap. Instead, he can kill it by edging forward, and once the spider drops, he can detach it from its web by using either the Slingshot or Sword. Once detached from its web, the Skulltula drops into the water and is killed.