What In The World???

What in the WORLD is this??? A Kumquat??

Seriously!  We were at North Head Lighthouse and we were walking the trail.  My mother in law saw this and I had to take a picture of it.  I'm hoping someone knows what it is. 

It was growing on the side of the tail and totally looked like it was a vine type plant, but the leaves and such couldn't be seen.  It really is crazy looking with all those spikes.

So go ahead and let me k now what you think it is....

I'm going with Kumquat (really I just like saying it...Kumquat...Kumquat...Kumquat)