this.x = x;

  this.y = y;

  this.r = 30;

  this.xdir = 1;

  this.grow = function() {

    this.r = this.r + 2;

  };

  this.shiftDown = function() {

    this.xdir *= -1;

    this.y += this.r;

  };

  this.move = function() {

    this.x = this.x + this.xdir;

  };

  this.show = function() {

    noStroke();

    fill(255, 0, 200, 150);

    beginShape();

    for (var theta = 0; theta < 4 * PI; theta += PI / 100) {

      var r = this.r * cos(1.5 * theta + PI / 2);

      var x = r * cos(theta) + this.x;

      var y = r * sin(theta) + this.y;

      vertex(x, y);

    }

    endShape(CLOSE);

    fill(255, 255, 0, 150);

    ellipse(this.x, this.y, this.r, this.r);

  };

}