Cactus Flower ?

As you can probably tell by today's blip, it's been dull and overcast all day ... (not that this picture indicates the weather very well, but if there's a chance of me capturing the sun, I normally try to) ... :o)
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So here, instead, is a picture of a flower that is just beginning to open up on a cactus plant which has been in a pot in the garden for as long as I can remember (which, knowing my memory, could be three seconds ago) ... :o/
Anyway, In all the years that it's probably been sitting in the garden, I don't think it's ever flowered before ... (but I might be wrong) ... (in fact I'm not even totally sure what type of cactus it is..??) ... (or, for that matter, if it even is a 'real' cactus, as the thorns don't actually hurt to touch ... ???) ... :o|
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I was going to say something else about this plant, but that was more than four seconds ago, so I've forgotten what it was ... :o\