LOL, Sort of M.C. Escher-ish.
Like, wow, you can copy and paste these .PNG's to your 'my spore creations/creatures', and the full creature appears in Sporepedia next time you start the game? What magic is this?
The magic of invisible layers in png files!
About the PNG's - they worked for me (gave creatures in the Sporepedia) when I started the game offline. I just copied the pics to 'my creations / creatures '. Obviously I couldn't get info/comments, but the creatures themselves displayed just fine.
I assume all the neccessary data for the creature is contained somewhere in the PNG file itself...