What are these weird tile things?

[Wafflesnaffler]

Does anyone know what these tiles might be made of please? They were underneath the normal bathroom tiles. If they were just a solid surface I wouldn't be confused (they look like some sort of sand & cement substance) but they are individual tiles...I've never come across something like this before. Any insight would be gratefully received - thank you!

Looks like some kind of breeze block material. How old is the house?? Could they have asbestos mixed in (as a kind fire retardant)? If so - you’ll need ppe to work with it. Not sure what, probably gloves and a suitably rated mask. @PigletJohn might know.

Asbestos

it might be a thick-bed mortar that old tiles were bedded in, still showing their marks after the tiles came off. Are the squares 100mm (4 inch) or 150mm (6 inch) square?

stand back and take a wider pic

How old is the house?

I believe it's a 60s property. Asbestos is what I'm paranoid about as it killed my Dad.

PigletJohn, that's a very good point - I think you might be right that it's just the impression of tiles, not actual tiles. Reasons being that 1) tiles would have gaps between them wouldn't they...if not grout and 2) in a close-up pic you can see that the line between two tiles doesn't go all the way through, it's just on the surface. Thank you so much for answering. Maybe I can feel a bit less scared for my husband, who revealed them and was exposed to some dust

Sorry forgot to say - 150mm not 100mm

Also forgot the close-up!!

That was my thought old plaster with embedded tile marks, and perhaps someone had shelf and holes are raw plug marks ?

Thank you everyone for your replies.

Are they under the painted bit of wall too? If they’re only under the tiles section I’d assume mortar, as why would anyone put asbestos only under the tiles...

It's mortar. As long as it's sound then just tile on top