Name: Diminish and Ascend staircase.

Age: It has been in the Christchurch Botanic Gardens in New Zealand since 2016. Before then, it was on display at the Sculpture by the Sea exhibition in Sydney.

So it’s a sculpture? Yes, by the New Zealand artist David McCracken. (Not to be confused with the Scottish footballer David McCracken.)

Appearance: A steel staircase that uses perspective to create the illusion of being never-ending.

A Stairway to heaven, you could say. You could. And if you were a gull, it might be an actual staircase to heaven.

Because a gull is unable to understand perspective, or conceptual art? Because a couple of them have been killed by Diminish and Ascend.

How? In order to give the impression of being infinite, the staircase ends in a spike. It’s quite hard to see when you are flying towards it at speed. Two gulls didn’t and impaled themselves.

Ouch! How has McCracken responded? He told the New Zealand website Stuff: “If somebody has a photo, I’d love to see it.”

Yeah, me too – gull kebabs! No, I don’t think he meant it like that. He also said: “Obviously, I have to do something about it.”

What could he do? He has mentioned removing the metal tip and replacing it with silicone painted to look like steel.

So that the gulls bounce off? That could also be fun. This is not about fun, it’s about not killing wildlife. And about art, of course.

Is it really art? Of course, although some may see it as pest control.

It sounds like a pretty unconventional form of pest control. Yes, and expensive, too: it’s not just the sculpture’s initial cost, NZ$192,000 (£98,000) from the council’s now defunct public art fund, but the NZ$700 a month it costs to maintain it that has concerned some councillors.

What maintenance? Contractors have to regularly wade into the lake in which it sits to water-blast it.

To remove? All the bird poo.

There is a poetic justice to that. I see, like: you poo on me, huh? So I kill you.

Do say: Something about how public art should challenge perceptions and communicate ideas, but never at the expense of the environment.

Don’t say: “Brilliant. Can we get a loan of it for Brighton?