Oil Change mishap - What was that thing?

[prismways]

So I just got my Boom Vader and I went to change the oil and inadvertently removed the wrong bolt that was right next to the oil plug bolt.

This really long spring and a cylinder with some horizontal holes dropped out. There was not much oil coming out either. I pushed the cylinder back in and awkwardly pushed the long coiled spring back up there.

What the heck did I disassemble and was there supposed to be a special way to re-install the cylinder and the spring?

Hoping I didn't mess up the engine or transmission.

thanks