@nooby123, if your code is used as soon as you add the worm to the world it will be eaten and another worm will be added and it will be eaten also, then another, and another... Using getX() and getY() would not be advisable here. Better would be Greenfoot.getRandomNumber(getWorld().getWidth()) and Greenfoot.getRandomNumber(getWorld().getHeight()). @yasumiishi, from within a sub-class of 'Actor', you can use 'getWorld()' to get a reference to the world that an actor is in. You can save it in a variable, and then use it to perform some method within the 'World' class: which would be preferable if you need a reference to the world for multiple operations. If you need the reference only one or two times, you could just use it directly: Please note that methods and variables that you create in your sub-class of World must be accessed differently.