Derek Adams

Hi all, When replacing the battery (normal car battery) on my 2013 C-Max Hybrid I found an odd hose that supposedly connects to the battery. Problem is that it does not fit into the side hole of the battery, either the old or new one. I checked to see if anything broke off and did not see anything. I have replaced a few batteries in my day and have never seen a hose like this. Anyone know what it is for? And more importantly do I HAVE to connect it?