Their bodies are orange and yellow spotted balls supported by legs covered in thorns. They are grass types.
Upon finding a smaller creature, they stand over it. Since their legs are covered in thick, sharp thorns, the creature is trapped beneath it. Then the Thornleg dives its head at the creature to catch it up in its mouth and swallows it. From the Thornleg's stomach, the creature suffers a fate similar to the prey of a Wriggler.