If you try to change the value by deleting the current value, the jellyfish vanish & do not come back even after typing a new value.<p>I have to add digits in front of the current value before deleting the existing digits, so that the field stays populated at all times, or the whole thing breaks. FYI.<p>Also if you put a really high speed, they sometimes swim off the screen & never return, even when lowering the speed. Pretty amusing.