I remember reading this book when I was 9 or 10. I might have been younger than 10, maybe 8 or so. In any case it was in 1998/1999 if I remember correctly. The actual book might have been published before 1998.
It featured illustrated stories about two strange alien creatures called "Blobs" and "Creeps". I remember them being small blob-like creatures with legs. They were in different colors. The Blobs were small and round and the Creeps were also round but with pointy edges.
I searched on Google for "blobs and creeps book" but it didn't show me the results I was looking for.