Answer
Elliptical paraboloid.
See image:
.
Work Step by Step
Comparing to Table 12.1, we recognize the form of the elliptical paraboloid (with -y and z interchanged).
This means that it opens along the y-axis (instead of the z-axis), and the minus tells us that it opens in the -y direction.
Cross-sections with $x=k$ and $z=k$ are parabolas;
with$y=-k$ the cross-sections are circles (special cases of parabolas).
