SCP-2558-J, known as Pufferkittens, are strange creatures currently in SCP containment. When undisturbed, they appear to be normal kittens, displaying an affection towards humans. When startled, they curl up into a ball of fluff of roughly the same size as a soccer ball, displaying a level of agility not commonly seen. Once disturbed, they begin mewling.
There are many varieties of 2558-J, the most dangerous being SCP-2558-J-ex, an explosive variant created when an unknown researcher put 2558-J through SCP-914 on the "Fine" setting. Although the explosive variety is lethal, being roughly as dangerous as a hand grenade, the Foundation has banned the weaponisation of all variants of SCP-2558-J.