Vellattam or Vellattu is an invocative ritual held prior to the actual Theyyam performance. The Nagakaali Vellattu is held for Nagakaali Theyyam, a fertility goddess worshiped by childless parents. Naga means serpent and Kali is the Mother Goddess. It is through Vellattam that the mortal human being is believed to transform himself into the divine persona. Equivalent to the Thottam (the invocatory chant) ritual, Vellattams are dynamic.