[Pharo-project] About (nil@nil)

with manuel oriol we started to play with the idea of a randomTester in Pharo. It poses a lot of questions. Now doing the first experiments, I found an instance of point (nil@nil) (besides reciprocal broken on Point (0@0) and (Point allInstances select: [:each | each x isNil]) first pointersTo points me to recreateSpecialObjectsArray I looked into the literals and others and I could not find. Each time I execute Smalltalk recreateSpecialObjectsArray I get a new nil@nil objects.... but forcing a GC garbage them. But I still have this nil@nil object around. Does anybody have an idea from where nil@nil could come from? Stef