Bathroom tiling over plaster

I pulled up the old tiles in the shower. They were mosaics.
Under them were 300 x 300 squares with paper and black dots. Perhaps felt.

Would these have asbestos in them?
Am i supposed to take them up as well?

 

Are the tiles ceramic or vinyl? Unlikely if ceramic.

Are these tiles dummy? If not, they could stay depending upon falls & if there's a step at the doorway (door will probably be short if to remove them).

You will need to waterproof over the tiles if you keep them or over the mortar bed if the tiler uses one - so check with the tiler if they're happy tiling over these or want them removed so they can lay the new tiles to falls.

 

Hi Scott,
After further looking and research and freaking out at the thought of asbestos, I think they are tile but came in the squares and were held together by paper stuck on the cement floor. Relief!
The whole floor is crooked so tiler will need to level it and then put new tiles down which will be a little higher than the last tiles.
So I will scrap off the remaining paper and mortar and then the tiler can level it all out.
I think the paper was getting wet and that made the interesting odour go though the whole house so am looking forward to a non odour house at the end of the project.
.