No, it's not some alien lifeform :-) Chrysalis (from Greek "χρυσαλλίς") or nympha is the pupal stage of a butterfly. Notice the butterfly's wings that have already formed? Best viewed Large, On Black  I found this one attached to my yard wall. I suspect it belonged to some species of family Pieridae, but I don't know for sure... This was one of my first macros with my "Canon EF 100mm f/2.8 Macro USM" lens, shot back in February, but I had forgotten to upload it! One morning a few weeks later, I found only an empty shell where this chrysalis was. A new butterfly had emerged...  UPDATE: This seems to belong to the Small White (Pieris rapae) butterfly, also known as "Cabbage White" or "Small Cabbage White". Thanks to tigerbeatlefreak for the ID. Seems logical, too, as I see those little butterflies quite a lot at this time of season around the house. I also posted a photo of this butterfly: Click here to see it