Facebook Poke, was released in 2012 to compete with Snapchat. The app never really gained any traction and its demise is somewhat expected.
Facebook Camera launched in May 2012 to let users share multiple photos fast. It was a pretty good app; however, its features have made it to the main Facebook app and thus may no longer have been necessary.
Currently, Facebook only has four apps on the App Store: Facebook, Facebook Messenger, Facebook Pages Manager, and Paper.