Found this web page http://bikeboosting.nl/index.php?id=86,0,0,1,0,0
and can't see your random piece.. It looks like a kinda cir-clip..?
On a similar note..
I watched an episode of the Amazing Race the other night.. They were were challenged to put together a model of the human body out of a pile of nine or ten pieces, and then ask the adjudicator if they'd succeeded when they'd finished. They hadn't been told that there were three redundant peices. This chick built [successfully] and tore down her completed puzzle three or four times before she realised the extra pieces were in fact not needed and she had finished the task long before.. Hmm