Melissa Harrison didn’t let this mystery stop her in her tracks. She’s spent the last couple of hours documenting a number of experiments to determine its origins, which included hitting it with a hammer six times (until it finally shattered) and trying to dissolve it in water.

There are a lot of theories as to where the #chimneyegg came from. A feasible theory suggests that it might be a bezoar stone, which are solid masses from the intestines of animals such as sheep or goats and that were used centuries ago as a poison cure-all. Twitter user lucyinglis stated that they were kept in chimneys for superstitious and pagan purposes, although I wasn’t able to confirm this elsewhere.

Another Twitter user hypothesized that it could’ve been an object eroded on a beach and dropped into the chimney by a bird.

Other less helpful suggestions have included it being owl poop, reindeer poop, and builder’s putty.

Harrison is taking all of this is in stride though.

Update: After getting inundated with suggestions and possible answers, Harrison posted on her blog with the final answer. Apparently, the mysterious egg-shaped object is bitter kola, which is a nut normally found in West Africa that can be chewed as a stimulant.

At last, we had an answer – all down to the amazing power of Twitter! Admittedly it wasn’t quite as interesting as a bezoar stone, but it was considerably more exotic and exciting than a bit of old putty; and it made sense, as there is a vibrant West African community around where I live in South London.

The only remaining mystery is this: who (or what) dropped it down my chimney?!