Thanks. This helps a lot. Two things: One, if I changed the ten to some int and slowly adjusted that int overtime to make it for example start with 3 spikes for the first minute of play, then 5 for the next minute, etc., would that work? And second, I have a loop where the spikes basically come forward (increasing in y) on the terrain, and once they are out of a certain value, they is changed back to the starting value. The spikes. remove(0); seems to remove them in the middle of the terrain. How could I make the remove happen simultaneously with my spike loop.