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First off, I have not read any of the books - sorry! But are you sure that it was extraterrestrial life? There are some books "Life after man" and such, which have pictures and (IIRC) short texts about hypothetical animals that evolved millions of years after humans are extinct.
Sanity is for the weakWell, if you are open to the idea that you may be misremembering, there is a creature in Man After Man that is aquatic, but can go on land inside a sort of "water bag". At one point one of these is punctured by another creature. But it is not a duck.
I'm having a hard time imagining why it would be a duck. There is no reason to think an extraterrestrial would be a duck. A duck is an inherently funny animal (there are more jokes about ducks than any other creature), could it have been a comedy book?
Edited by KEVPI'm familiar with that illustration in Man After Man. I have a hard time imagining how my mind could have distorted that into the thing I remember. IIRC the "duck" didn't look that much like a duck. It was like an unhatched chick, all veiny and featherless but still birdy. My mother called it a duck.
The National Geographic book I mention above is probably the explanation. There is a bag alien from Jupiter being punctured by a predator, and separate aliens from Titan that are sort of like embryonic birds. My memory probably conflated the two. Here's what I'm walking about: http://www.gamingsteve.com/blab/index.php?topic=13687.0

In the late '80s or maybe early '90s I was shown a book or maybe magazine article that showed hypothetical alien life. The one that really stuck in my head was this duck in a transparent organic bag. A predator was breaking into the bag to eat the duck. I remember it being photographs, like of realistic models, but it might have been very good paintings.
Just to get this out of the way, it's not Extraterrestrials: A Field Guide for Earthlings, A Tour of the Universe, Alien Landscapes, Galactic Aliens, the book of Cosmos, Expedition, Barlowe's Guide to Extraterrestrials, or Is Anybody out There? It's possible that it's The National Geographic Picture Atlas of Our Universe. It's also come to my attention that it might be Life off Earth by Ian Ridpath. Maybe somebody who's read these books can confirm or deny?
Edited by FloydPinkerton