The Conjure Animals Spell doesn't seem to have any limitations on what you can conjure beside the number per CR, and that they have to be beasts. Seemingly you could conjure a creature that you've never seen before. Wild Shape on the other hand makes the distinction that you can only assume the shape of a beast that you have seen before. Is this a loop hole for Wild Shape? Could you conjure a Giant Owl, "see it", and then Wild Shape into a Giant Owl later?
Some of the distinctions that are making this tricky for me is that with the Conjure Animal Spell you aren't actually conjuring creatures, but "You summon fey spirits that take the form of beasts" (PHB 225). I'm interpreting this as these aren't actual beasts, merely impostors. There's something just not entirely real about these creatures, so they don't count as a creature that a druid has seen in the wild.
On the other hand, with Wild Shape you aren't actually turning into a real creature either, but you "assume the shape of a beast that you have seen before" (PHB 66). So maybe seeing the shape of the beast is enough to transform into it.
So, does a spirit in the form of a beast summoned with the Conjure Animal Spell count towards a creature that a druid has seen and can now Wild Shape into? Does it matter that it is a spirit and not a real creature, or is seeing its an impersonation or its shape enough for a druid to Wild Shape into it?