This dosn't taste like Chicken! - Help with a story Idea

Warning for my Roll 20 group if any of you are lurking here - spoilers ahead so please do not read!

Hello guys and gals, I'm looking for some inspiration for a story idea I've had but am having trouble developing myself.

My group has been going for a while now and one of the player characters decided they wanted to have a festival arranged around the aegis of the hearth ritual cast at the winter solstice. This, of course, began as a small scale thing for the coven folk but rapidly descended into a significantly larger event, with a whole list of invited local notables and a rearranging of the time to allow other local mages to come and not miss their own aegis of the hearth rituals.

Anyway, they broke up all the different jobs and assigned them to the council members. The main goal is to show off as much as possible. To this end my magus character (the guy who is always in the background looking after things as I'm the storyteller) has been tasked with creating a ritual to create a large feast for all the guests - a waste of vis but a flashy way of both showing off his abilities and also sending the message that the PC's covenant has power and wealth to be able to use vis on something so frivolous as having fresh summer fruits on the table in wintertime.

Now, here is where the story idea comes in. The character I am playing is from one of the published adventures in tales of mythic Europe, Severin from the fall and rise story, which is the story I started my campaign off on. Severin is a magus who was kidnapped by a fay and finally reappeared back in mythic Europe after being trapped for years and years of 'real' time (in this case literal centuries).

Now, my idea for a possible story would be something along these lines - the feast created by Severin contains a meat that no one recognises. When asked what creature it is, he names an animal no one has heard of, and of which no historical record can be found at all - which mystifies Severin as it was such a popular meat and eaten widely before he was kidnapped. This is as far as I have got, setting out the mystery as it were, but I cannot think of how to spin this into something more interesting for an adventure or research for the characters to follow up on.

My best idea was trying to work this into something revolving around the Voynich manuscript, but I'm still mulling it over and I'd love to hear some other ideas if anyone wants to put forward their ideas.

So, my question to you would be, what do you think this mystery meat is, why does no one today know of this meat and why can no one find any mention of it in the books they have access to?

Well, this would have made a great Games From Folktales article...

If you want conventional animals, I'd suggest the aurochs or the ortolan. The aurochs is extinct in Western Europe in 1220, and only eaten by kings and senior nobles in Eastern Europe.
Ortolans are still known in the modern day, but they are so rare that eating one is so sinful that, by tradition, you wear a towel over your head to hide from the eyes of God.

If you want something weirder: the turn of the age in 1000AD changed the word and there are different animals in it now, or to steal a little from Nobilis, perhaps there is a type of faerie that feeds on the very idea of a thing? The memory of the thing has been consumed completely, but now that Severin has caused it to be remember, it is again available and the Mneomophage comes for anyone who remembers the beast at the feast. If you kill it, you find souvenirs in its lair of things it has eaten into forgoteness, and these provide Original Reasearch materials, or a collection using the museum rules in covenants. If you can capture it and interrogate it with Mentem, you discover it is but one of its type, the mother of this thing was let loose into the world by the Guernicus to eat away Diedne magic by destroing all memory of their god. Lacking a better idea for the moment, I'd make her Ammit the Eater of Hearts.

(Alternatively, this could be a weapon from the titanomachy, used by the titans to kill faerie gods, stirred up for the war against by Diedne by House Tytalus.)

Oh: if you only want one mnemophage, the creature at the feast was sacred to Diedne's gods, and was her familiar, ergo it was eaten with the memory of the gods.

I love this idea - heck I'm seeing the basis for a whole saga centred around Bjorner Magi.

What if now this creature is re-remembered then all of a sudden several failed Bjorner apprentices that went to other houses find they suddenly have access to this creature as a heart beast? How would house Bjorner react to this - I'd imagine they'd be pretty annoyed at the possibility of several generations of potential bjorner going to other houses because they failed to transform into their heart beast because of House Guernicus' magic basically editing it out of existence during the schism war.

Finding out what has happened and why could become a completely separate grand quest for a group of bjorner Magi - and there would probably be the mass prosecution of house Guernicus by these magi with this new heart beast for depriving them of magical power - assuming it can be tracked down to house Guernicus. This would also lead to players probably being instrumental in a grand tribunal, as I'm pretty sure that's where this kind of dispute would end up.

Would this change how Bjorner see failed apprentices - would they still be passed on to others or would they be viewed as evidence of further tampering with the world by others - maybe a new group or mystery cult within house bjorner would form to seek out and find these 'missing' animals.

This wouldn't work in my current saga but as rabbit holes go that's a fairly deep one

Go for one of the ice age mega-fauna, but give a half mythical description without reference to it's modern name.
It's unlikely any of the characters have seen an elephant - so an 'ordinary' mammoth (high on the early human menu) will be a serious shock. Also the then extinct Irish elk were referenced in the Ireland tribunal book.