I've always just known this as the Pigeon Park sculpture -- but it does have a proper name: "Karangahape Rocks". Surprising fact (for me) number two: it's really a fountain., installed in 1968. The design, by Greer Twiss, features figures sitting amongst river stones smoothede by endless flows of water. Except, the water hasn't flowed for some time now. Some info here (scroll down).
The land was formerly an unused part of the Jewish section of the Symonds Street Cemetery, until it was vested in the Auckland City Council. Which is why I thought the sculpture was some sort of abstract Holocaust memorial. (This is why, these days, I like to try digging to find out more about things.)