Ball Cactus fruit

Macro shot of what I seem to remember was a Ball Cactus fruit. Two friends and I joined a group of people from Medicine Hat College on 21 September 2013, to go and monitor some Yucca plants in SE Alberta. On the walk into the area at Pinhorn Grazing Lease, someone showed us this very small Ball Cactus fruit and told us it was edible. I got the chance to eat it - and it was delicious.