Prismatic

Here's a guessing game for you :)

I'm sure some will figure out what this is immediately, but I'd love to hear what you think it is.

Taken with my Pentacon AV and extension tube.

 

Well, most of you were right about the glass. It is a drinking glass with a striped coloured coaster underneath. I shot into the glass at an angle, and got the colourful reflections on the glass table. Thanks for playing along :)

Done