Janet Tweedy wrote:

Very Strange thing - the pub sign,
well painted and clear had The Pineapple on it and a large picture of a
pine cone!

Talking about very strange things that look like a cross between a
pineapple and a pine cone ...

While hacking at some brambles, I came across this, about 4" long, quite
firm and at ground level.

http://adslpipe.co.uk/photos/giant.jpg

I first assumed it was a blackberry that had mutated from previous
sprayings, but someone else identified it as a gall, which seems to make
sense, especially as the brambles haven't fruited.

What's the mechanism for things like that to grow? Does the invading
bacteria trigger the plant's "stem cells" and somehow this happens to
have triggered part of the bramble that was destined to become the fruit
to grow like mad?