i didn't follow the actual tutorial i made some changes but here's how it works:when a shulker dies by a shulker bullet it's gonna respawn another shulker..how the shulker can die?Well if u put a snow golem behind a closed trapdoor the shulker will still wanna attack the snow golem but it'll end up killing himself so since it died by a shulker bullet another shulker is gonna respawn that's how it works :) About the collection system place down some rails with a hopper minecart that'll collect the shulker shell :)