They look like coasters, but they're actually bespoke cookies, made by Pooky Amsterdam (best known for her work in Second Life, but she's been making weird cookies for decades — she first gave me some in 2003). The pictures on these are of Essex University, but that's not going to save them. There are only two left as I write this...
There are a number of strange things about these cookies. Firstly, they're quite thin, but there's a lot more to them once you start eating them — they're surprisingly filling. Secondly, the colour goes all the way through, it's not just sprayed on or anything, it's like a marbling effect. Thirdly, they don't look like shortbread but they taste like shortbread. I love shortbread! Fourthly, they're better undunked than dunked. Fifthly, they have a natural grain to them so they snap better one way (lengthwise) than the other.
I've no idea what they're made of (maybe cookie dough is involved at some point?) but I don't really care so long as it's not going to kill me. It's cheered me up in the middle of two batches of marking, and blogging about them has enabled me to procrastinate further.
I think I'll keep the last two for when I need cheering up in the middle of writing Christmas cards.