This seemed like a pyramid but was not. Your teacher came hearing the noise from the lab and Karan, who had the object asked him what it was and about its shape. Then the teacher told that its shape and name are same which is
A prism is a 3D shape with an n-sided polygonal base, another congruent parallel base, and n other faces (necessarily all parallelograms) joining corresponding sides of the two bases. All cross-sections parallel to the base faces are congruent to the bases.