Wow, it looks like it has a second membrane or something. Is there egg white between it and the shell? At first I thought it was wrapped in artificial cobwebbing for Halloween!
Yesterday I found a rubber egg for the first time (shell-less). I squawked when I touched it, then (because in the dim light it looked normal) asked my daughter to touch it. Nothing fazes her. This did. Of course I had to try it on my son and my husband. Son yelped and ran to wash his hands. Husband said "never show me something like that again." Heh.