Does anyone know what this is?
 

I found it today. It's flattish, shaped roughly like an equilateral triangle with 3" sides, and very heavy. It feels like iron. It's covered on both sides with a beautiful iridescent enamel with thumb-size depressions in the three corners and semicircular cut-outs in the sides. There's a hole in the centre with a decorative surround.

Is it a paperweight or something to fidget with, like those spinners that were so popular last year?

A Japanese throwing star?

A Shuriken.

A.k.a. Throwing star

It's completely blunt. Shouldn't a throwing star have sharp edges and points?

Throwing stars that are meant to be used are sharp. Ornamental throwing stars are sold blunt as they're not really meant to be used, they're meant to be pretty.

A base that a mysterious something once plugged into? Does the hole show signs of wear inside?

I don't know. It's too small to see inside. But there are signs of damage on one side of the device, so perhaps it was the base of something.

It's a part of a time machine.!

Not to insult your drawing abilities, but you can't post a real picture?

A blade for a bush trimmer...?

A photo would definitely help.

Haven't got a webcam! I only have v-e-r-y occasional use for one so not worth buying.

I carry a camera in my pocket - occasionally it gets used as a phone ... maybe you have something similar ?.

Nope! You ought to know by now that I don't approve of smartphones or any 21st century technology. Can't cope with it! Too old!!

An image search for shuriken:
very few are triangular, but they do exist: https://fanfitgaming.com/wp-content/...904_grande.jpg
Here's one with four points that has the iridescent sheen that hazel mentions: https://allninjagear.com/images/thum...riken-set.jpeg

My first thought was something used in construction, holding 3 things together (or apart), possibly with a screw through the middle - does it show signs of wear and usage that could be indicative of that, or does it look purely decorative?

What about a scanner? If the lid can't be closed then putting a sheet of paper behind it should do it.