drowned in a barrel

i had an idea for a new infested block similar to the silver fish only this time its a barrel or chest that could be found in an underwater ruin where if you mine or open the chest, it would disappear and in its place would be a group of 2 - 4 baby drowned ready to destroy whoever disturbed their nap which could be every 10 to 20 percent of chests just to spice things up for those who dare to dive into long since lost dangers.