"my neighbour says it is from space."

No, it's not.

Anything which entered the earth's atmosphere from space would be travelling at high speed, and if it survived the trip through our atmosphere without burning up its terminal velocity would be such that it would probably have passed straight through your conservatory roof.

The object has almost certainly been dropped by a bird.

Why not try contacting your local newspaper, they might have an answer?.

Well off the mark I know, but the other week we heard a bang, went out to investigate, and found some 'yobs' making an hasty retreat. We were never able to find what caused that 'bang', but it was sure loud, and the double glazing was still intact?.

There was also an incident a few months again, when a number of properties (I missed out!) in my area got 'peppered' by what appeared to be ice cubes of various shapes and sizes. That was eventually traced back to a possibility of 'ice formations' from a over flying aircraft. There are a large amount of aircraft overhead daily. The authorities could not trace the possibility of the aircraft involved, due to the volume of air traffic and no other reports from any aircraft. Luckily there was no major damage to property or injury to person, but all the same it might well have been?.