What is this?
So this appeared:
There used to be a Eryngium 'Neptune's gold' in roughly the same location which has a similar lime green colour.
Trouble is that it died last year and was removed.
So possibly it wasn't fully dead and a piece of root remained which is now regrowing, or it is a seedling.
The new shoots last year looked completely different to this. It looks more like a seedling to me. If it is a seedling, then it is most likely to grow to be very different from the original.