An activity is supposedly destroyed. Yet, It's recreated by android without me explicitly starting it?

So, I'm facing a strange behavior. I'm implementing MVP design pattern in my app. I have 2 activities, A and B. The presenter of activity A is listening to a socket connection to the server. In the activity's onDestroy() method, I call a method to unregister the presenter from the socket helper class.

In case of a certain message "TYPE X" from the socket, I start a new activity B. The onDestroy() method is called normally, and the socket listener is unregistered.

Here's the weird part. When receiving a message of the same TYPE "X", activity A is recreated and activity B is restarted, repeating the whole cycle again.

The activity A:

@Override
protected void onDestroy() {
    mainActivityPresenter.terminate();
    // some code
    super.onDestroy();
}

The presenter:

@Override
public void terminate() {
    socketHelper.unregisterListener(socketListener);
}

Does anyone have an explanation for this behavior?