OOO is kind of odd. During most of the show, it worked like how W and Fourze do regarding monsters and their effects on normal people. However, a few later monsters actually killed people (the first two dinosaur yummies)... but they don't try to make any kind of plot point about it and the characters react as usual. They might as well have survived, considering how the script was written, although it's obvious that they didn't. They also stop immediately afterwards and go back to the usual pattern. However, in the final arc, the Greeeds themselves started killing people again, and this time the deaths aren't completely ignored, but still mostly glossed over.