This morning my iphone showed me a memories photo reel but those photos had been deleted from my phone a long time ago?

So, I woke up this morning and my iPhone comes up with a photo memory reel from May 2014. So I click on it and it shows me about 10 photos that I had taken on a holiday to Ibiza but I had deleted them a long time ago - maybe 2/3 years ago. So these photos are not on my iPhone and I can’t see them in my iCloud either, so where and how has my iPhone got them from?