I have been trying to draw this out for an hour now and cannot visualize it.
$x$ is between $0$ and $1$, $y$ is between $0$ and $x$, and $z$ is between $x^{2}+y^{2}$.
The $z$ line is just a parabola while the others are simple lines but I cannot figure out how to draw it or represent it in comprehensive way.
It's the solid with a parabola as a top and a flat, isosceles triangle as a base.