Opossums may have a very strange stigma that follow them, however they are actually very beneficial and just down right interesting critters.  First off they are the only Marsupials in Pennsylvania. They have a much on their bellies to keep the littles ones in when they are first born and also have a flues tail that allows them to carry bedding material if need be.  Opossums are natures tick control squad, being able to eat ticks by the thousands.  These lightly white and grey colored critters like to live in easily habitable areas.  When they are out foraging, and danger is near by they will lay down and mimic the appearance and smell of a sick animal, while also having the ability to be very agile.  Opossums are immune to Rattlesnake venom and pit Vipers, allowing them to regularly prey on them.