If it smells like ammonia, it could very possibly be mould.

And it's spelled mould up here uber. I suggest you read up on your UK/US english differences.
JohnnyZ Reviewed by JohnnyZ on . Possible Mould? Found possible mould on weed. I've left it for about a week and it was quite wet when I got it. That said I've left weed for up to a month before and never had an issue Some parts of it were whiter than usual, although not so much in a 'web' kind of way that I've seen pictures of. It's been left in baggies and squished against the side during transport. The parts were it had been a bit squished were just whiter and paler than normal. There were also lots of yellowish dots around the buds Rating: 5