Facebook have come up with a powerful new feature which is a new way of showing your current status and more ways to express yourselves to friends on the Facebook Messenger called "Your Emoji".
This feature lets you to display chosen emoji on to your Facebook Messenger Profile pic for a day (24 hours) similar to that of Whatsapp status, in a way to let people know with much more ease what they are up to, how they feel or indicate that they are busy etc..
You can view these emojis on the Action tab in your Facebook Messenger for now but we can expect further integration where it would be much more visible like in the inbox and message thread.
It is currently in testing phase and will be roll out for all users in coming weeks.