I'm Not Joking, This Plurals Quiz Is Actually Really Challenging

Fish and fishes are both generally accepted as the plural form of fish.

Yep! As weird as it may sound, culs-de-sac is the right plural. Cul-de-sacs is also correct.

Octopi is often mistaken as the plural of octopus and is even listed in some dictionaries. But because the word is originally Greek and not Latin, the *more* correct forms are octopods/octopodes and octopuses.

The plural of moose is just moose! Nothing changes. Deer and sheep are two other words that don't change in their plural forms.

Media is the plural of medium, and mediae is the plural of media!

Beefs and beeves are both acceptable plurals of the word; beef is strictly singular.

Opera is already plural! Opus is the singular form. Who'd a thunk?

Indexes and indices are both correct plurals of index!

Lasagne is also a correct plural.