Based in the picture, the paths made an hourglass symbol. With two paths; the first path forms into Z, and the other forms into S that bloons cross together in the middle of the track. Once the timer runs out, the hour glass will flip and the path's direction changed; instead the bloons will go on top, they will go on bottom as like in-reversed mode. No water. The particles are just colored blue to make the track nicer and clearer effect. Available on Co-op Mode.