3.0l Trailing Arm Qestion what broke off?

[colb]

Was sent this picture by one of our Zed Shed Cymru members asking what broke off his trailing arm? Anyone know?

 

[GazHyde]

If you are talking about the hole just by your index finger it’s a rubber plug which holds the oil inside the arm. They are charged with oil from the factory to stop them corroding from the inside.