Probably because it's produced it. That's what they look like. I've never sown the seed (there will be up to 8 or so in each fruit), but someone on this site may well have done.

I'd be tempted to sow them in a cold greenhouse or frame, do it now and cover with net to protect from vermin then wait and see......if any germinate next year pot on....I did it with magnolia seeds and have a small tree growing, it will I'm sure be a few years before I see a flower.....even then it could be lovely, or ver disappointing!

They do grow quite easily from seed. I had a lovely white flowered species until the bad Winter two years ago, which I had grown from seed.
No specialist treatment needed, no heat, just protection from rodents and a lot of patience.