What plant is this?

[bumblingbovine49]

Very inexperienced gardener here. I noticed this today in my geraniums so dug it up assuming it is was weed I had missed in my regular hoeing/pulling up of smaller weeds. The tuba root surprised me a bit though.

What is it? Should I have pulled it up?

I have a tiny Garden so not too keen on things that run wild/ spread too quickly but if it is not too aggressive and is pretty I am happy to leave some

its a horse chestnut, growing from the seed (conker).

Ok. Thanks. I did think the root looked like a conker but we don't have any of those trees adjoining our garden. Still nature is a wonderous thing
😁

If you've got squirrels nearby, then the conker was probably buried by one of them, look for more seeds sprouting and remove them, a conker tree can be lovely but a bit overwhelming in a small garden.