Does anyone know what these are?

[Metaplasia]

And why are they all over my house? I mean obviously they're some sort of beetle but should I be concerned? I've deep cleaned and can't find anything, they just randomly appear. Help!

Looks like a carpet beetle from a quick google.

Carpet beetles, sorry. You will also find little cute larvae, they climb walls and hide in fabrics and eat holes in your stuff.

A pet flea spray will get rid of them but you will need to go through all your fabric items and check them, wash, dry and put in sealed bags if you want to get rid of them.

Use a crevice tool on your vacuum cleaner and get right in and under the skirting boards and behind your fridge/cooker/wherever your toaster is kept.

They're annoying, but doing that (along with the spray) should get rid of them quickly enough - especially if you make a point of ensuring no crumbs or food is left on the floor

Thank you! I vacuum every day and clean the sofa regularly because of the dog hair but will be more thorough, chuck the throws on a boil wash and get some flea spray.

They might still get in through a window so you will need to top up the spray every 6 months, it is the larvae that cause the holes. Also check if there are any old birds nests in the loft/vents etc. or fur items in the house, they like animal fur, and also gaps around skirtings and between floorboards.