Subject line says it all, check yourself,

(Heap withAll: 'array') reject: [:x | x = $r]

What's the rationale (there's no doc, no comment)? Archive shows that  
#species was changed to fix another (anonymous) bug but, this way the  
senders of #species can impossibly do what Smalltalk users expect from the  
collection hierarchy (and there is #asArray ...)

-  
http://lists.squeakfoundation.org/pipermail/squeak-dev/2000-March/011043.html

/Klaus

P.S. Heap is used in not-so-uncritical parts, like #startTimerEventLoop  
and WorldState, so I don't want to "just" play with Heap's #species  
without any background info on what was fixed.