Koopa Paratroopas are a type of Koopa Troopa with wings. They are described as afraid to go anywhere other than the ledge they're on. Which can make it a hassle to get past them on the account that you either have to dodge it or kill it because it won't walk over the ledge and kill itself. If there are multiple Koopa Paratroopas you can bounce on their head to keep afloat. Though note that if you perform this tactic, the Paratroopa will fall to its death (or to the platform below) just after one bounce.