All at once? If so:
*I turn the mass towards the tree you're pointing at and make it's head and upper body move backwards as I manipulate the shape of the head so that front part of it is cut horizontally towards the back of the head and stops at the middle of each side. The mass then thrusts it's head forward and opens it's newly formed mouth as I form small, sharp points in a line around the edges of the inside of it.*
*I turn the mass towards the tree you're pointing at and make it's head and upper body move backwards as I manipulate the shape of the head so that front part of it is cut horizontally towards the back of the head and stops at the middle of each side. The mass then thrusts it's head forward and opens it's newly formed mouth as I form small, sharp points in a line around the edges of the inside of it.*