[Zope] Analyzing ZODB objects

What is a good tool for analyzing the size of each object in the ZODB, pickled and unpacked in memory? I'm using Zope 2.6.2. With 62,214 objects in memory, the server uses 491MB of RAM. That gives roughly 8kb per object, assuming other things aren't don't contribute to memory usage as well. Is there any way to predict how much memory is going to be used? Bye, -- Bjorn