Good Friday

Spring has FINALLY sprung in our neck of the woods. The Japanese Magnolias are mostly in full bloom.
The poppies, thrift, and heather are decorating the flower beds, with irises to come shortly.

Then there's this thorny thing. It's awful. It reminds me of the thorns depicted for the Crown of Thorns in most art of the crucifixion of Jesus. Most of the year it is just green stems with massive sharp thorns that could cause great bodily harm, easily put out your eye, and possibly very serious injury if you fell into it. We have several of these nasty things growing on our property, and they are invasive and dangerous to be around. But for a couple of weeks each year around Easter, some of the more mature bushes will get these very lovely, delicate white flowers amongst the thorns.

The flowers do mature to a citrus like fruit that is yellow or orange, mostly full of slimy seeds, and something I would not eat.

What is this thing?