First sighting the shell was much greener and softer (no pic). The shell hardened over the span of about a week and cracked open (pic). Four seeds inside, shell size is about a cubic inch.
Was there any resin / sticky material associated with the seeds? This looks like a Pittosporum fruit but the seeds look overly large for that genus
No, the seeds were dry.
OK - Try Camellia (Theaceae) - see https://http://www.google.com/search?q=Theaceae+Fruits&client=firefox-b&source=lnms&tbm=isch&sa=X&ved=0ahUKEwic14LfneXZAhUHHpQKHegvCYgQ_AUICigB&biw=1635&bih=905#imgrc=OV94AanYsm9b6M:
So that link doesn't seem to work but either way have a Google and see what you get under images for "Camellia Fruits"
I think you're spot on with the Camellia seed, the images I found look very similar. Thanks Peter :)
(JPG format, max 500kB)
First sighting the shell was much greener and softer (no pic). The shell hardened over the span of about a week and cracked open (pic). Four seeds inside, shell size is about a cubic inch.