Egg
The cross section, of a 3D object, is the 2D shape made when a 2D plane cuts across the 3D object. Often "cross section" refers to the shape made when the plane is at right angles to an axis of the 3D object but this need not be the case.
The shape of an egg.
A cylinder is a 3D shape that has the same cross-section along its entire length. This means that if you slice the cylinder parallel to its bases, each cross-section will be identical to the others. Other examples include prisms, where the cross-section is a constant polygon along its height.
The following are some shapes having a square cross section: a cube, a cuboid, a square pyramid.
The shape of the cross section depends on the 3D object being sliced. For example, if you slice through a cylinder horizontally, the cross section would be a circle. If you cut through a cube diagonally, the cross section could be a triangle or a rectangle, depending on the angle of the cut. Thus, the specific 2D shape observed in the cross section varies based on the object's geometry and the orientation of the cut.
The cross section, of a 3D object, is the 2D shape made when a 2D plane cuts across the 3D object. Often "cross section" refers to the shape made when the plane is at right angles to an axis of the 3D object but this need not be the case.
The shape of an egg.
Prism
An oval 3D shape is called an ellipsoid. It is a three-dimensional shape that is similar to a stretched out sphere.
a 3d oval is called an ovoid and it looks like a type of egg
The following are some shapes having a square cross section: a cube, a cuboid, a square pyramid.
2-Dimensional
oval
The shape of the cross section depends on the 3D object being sliced. For example, if you slice through a cylinder horizontally, the cross section would be a circle. If you cut through a cube diagonally, the cross section could be a triangle or a rectangle, depending on the angle of the cut. Thus, the specific 2D shape observed in the cross section varies based on the object's geometry and the orientation of the cut.
Ellipsoid. (An oval is a 2-d shape, NOT 3-d).
A square cross-section cuboid would fit the given description
An hexagonal cross-section prism would fit the given description.