I choose to believe that those 22% were all just being pedantic about the definition of the word “shell” and whether a cell membrane constitutes a shell.
Because the alternative is just too disquieting.
I started Googling and, nope. After fertilization a vitelline membrane forms around the new zygote, but that's different from an eggshell, it's really quite separate, as you can tell if you crack a chicken egg: it's there in the chicken egg under the eggshell.
Do get "zinc sparks" though.
"in a poll in August 2020 whether it was true that “most women get their period on the first of the month,” 75 percent got the right answer — false — but a notable 21 percent said they were “not sure.”"
It's definitely not 22% being pedantic.
To be fair I wasn’t sure but that was because my immediate thought was “shell” referred to (as you said) a kind of membrane and not…literally, cause who would believe that 🤦🏼