The bronze ram is hollow in the back, it sockets into a thick piece of timber sticking out forward of the hull.

https://i.imgur.com/tsW61ob.jpg

After ramming, they were suppose to back the ship up with oars to allow water to flood into the holed ship, but on some occasions they could get jammed in with the target - which is why most rams were made as short as possible so they won't get stuck as easily.