Thanks for playing along. 

The answers…

“They are all more intelligent than an American toddler.”

“eyeball pupil thingy” (see above)

“freakish eyeballs”

“They are all animals."  uh-oh

"All have at least tissue level organization, unlike sponges who do not have tissues.” Uh-oh again, but for a different reason.

Indeed, the correct answer, as many of you know-rectangular pupils.

And for those of you who were not paying attention…