Do you know from where in Australia, Andrea? A more precise location might prompt someone to respond to your post. It might also help in pin pointing its origin. It might also be a seed from a non-indigenous plant which might make it more difficult to say precisely where it came from.

If you are overseas did the person importing the seed have permission? I ask this because many seeds are transported away from their natural locations & become invasive weeds.

I suspect it came from NSW,but don't know much. I'd like to identify it also because I don't know if it's potentially invasive,but I'm not planning on sowing it anyway,I just keep some seeds for the shape as a small collection in jars.

Sorry, Andrea, but you'll need to rely on the expertise of someone else with this one.

There's nothing in the frame to indicate size (just a little hint if you are posting again, please include a coin, ruler, pencil etc so we can see the actual size).

I think it's a quandong seed --- the seed kernel...... Eleocarpus species. check out pictures

https://www.google.com.au/search?q=quandong+seed+kernel&rlz=1C1CHMO_en-GBAU666AU666&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiynuvJ4K7MAhUOv5QKHbR3CoYQ_AUIBygB&biw=1073&bih=898

Yes! It definitely looks like an Eleocarpus ganitrus, thank you very much! I'm good with ID keys for trees, but really don't know where to start when it comes to seeds. Thank you again.