Sn.

SN, Sn, sn, What could it be? A little abbreviation, For all to see. In science and nature, SN stands tall, It's the symbol for tin, A metal for all. But wait, there's more, Sn has another role, In astronomy it's supernova, A sight to behold. And in writing, .sn is quite neat, It's a file extension, For websites, oh so sweet. So remember, my friends, SN, Sn, sn, They have meanings, In many a den. Random page: Owari no Stella