This is pretty much unbelievable.
My first impression is that this is a plaster cast of a mummy. With some additions like the extended fingers. (which would have been done before the cast was made.)
But from a photo it is just a guess, I could tell you if it was plaster or not in about 10 seconds if I had even a very minute sample.
It reminds me of the casts made at Herculaneum and Pompeii*:
This poor soul was trapped and died in Volcanic debris, when Archeologists found the impression (the hole in the ash where the body had been) they poured in plaster. you can see that it manages to capture quite a lot of detail. There are a lot more similar casts, although they are very interesting, I find it hard to look at them because they capture such tragedy.
But for anyone interested you can find more here by google searching for* "pompeii and herculaneum plaster casts".
Like I said I can't say from a photograph if it is plaster or not.
It is possible that the body was 'bleached' by the local conditions it was 'buried' in.
I understand that it came from a cave in Nazca, which is extremely arid. So the desiccation process might have destroyed or leached out the colour.
It is not an 'Egyptian' type of mummy. The Egyptians used something called mummia (a sort of tar or pitch) in the preservation (embalming) process, that is where we get the word mummy from.
I believe that the American ones are 'mummified' by the desert conditions, but I would expect to see more variation in colour of the outer skin, especially on folds etc where the colour leaching process had been inhibited.
I would also expect to see some textiles (cloth) that 'wrapped' the body. And also other grave goods. Where are they?
The problem with an 'artifact' like this is that it has no provenance and no context. We are expected to take Jaime's word AGAIN!
With the last one (roswell slides mummy) I argued against it being a "Dummy" or model, but with this one the fakery is pretty obvious.
I think the fingers are a dead give away.
My conclusion is that it is a cast made from a real 'mummy' with some alterations and additions.
If I could tell you if it was made of plaster in ten seconds, then somebody not used to the material could tell you in under a minute, provided they had understood the basics.
There are varying degrees of test and they range from free to thousands. but the most simple is to smell it and 'bite' it (literally use one of your canine teeth to feel for its texture) Plaster and 'mummified' skin would have a totally different texture. If you don't fancy eating a bit of ancient jerky then just weigh it, even a hollow plaster cast would weigh significantly more than a desiccated mummy. A cheap chemical test would be the next option.
Anyway there is no excuse if it turns out to be a 'cast' plaster or otherwise (it may be made from resin or other casting material). finding out should cost less than a ticket to the 'event'.
Just to demonstrate what you can do with plaster:
This is a plaster replica of Trajun's column.
Here is a mould and plaster cast of human teeth.
Plaster cast of teeth from front.
moulage sur nature (moulding on nature)
Plaster cast of lower part of a human.
here is a page about plaster casting:
Krishna and the Plaster Cast. Translating the Cambodian Temple of Angkor Wat in the French Colonial Period | Falser | Transcultural Studies
