Here is a pesesh-kef (this example is from the Museum of Fine Arts Boston, 11.765)
Here is a fish-tailed knife from the Petrie Museum (UC10244).
And if you want to know why they are different the best paper is Thomas Hikade's 'Getting the Ritual Right'. You can find it online here. And he has lots of references about the things. I would like to 'talk' more about these because they are flinty, but must move on....
People also know about the model adzes waved in front of the mummy too. Here you can see a detail of a piece of the Book of the Dead in the Egypt Centre showing the priest on the far right waving things at the mummy. The adze is on the top of his heap of magic tools and you can see the foreleg of an ox under that.
And, if you want to know more about this fragment of the Book of the Dead, click here.
Well what about this:
Things like this have proved a bit of a mystery to Egyptologists, and have been considered granaries or even cosmetic containers! However,a few years back I was privileged to hear Silke Grallert talk about them. It seems they were used in the Opening of the Mouth Ceremony from the 26th Dynasty. And if you want to know more, here is the link.
Of course, I can't actually resist flints. So, a picture, not very good I'm afraid of some miniature polished stone knives from a photo I took in Cairo Museum in 2003. They are from the tomb of Tutankhamun.
Similar ones were found in KV55. Their context suggests they were part of the 18th Dynasty Opening of the Mouth 'toolkit' put in tombs. Such things aren't listed in texts, or drawn on tomb walls in association with the Opening of the Mouth ritual.