The planet that can be called a "star that never was" is Jupiter.

Here's why:

* Massive: Jupiter is the largest planet in our solar system, with a mass about 2.5 times greater than all the other planets combined. It's incredibly massive.

* Composition: Jupiter is primarily composed of hydrogen and helium, the same elements that make up stars.

* Internal Pressure: Due to its immense gravity, Jupiter has immense pressure in its core. This pressure is so great that it's thought to be on the verge of nuclear fusion, the process that powers stars.

However, Jupiter lacks the necessary mass to ignite nuclear fusion. If it were about 80 times more massive, it would have become a star instead of a planet.

So, while Jupiter is not a star, it is a massive ball of gas with the potential to be one. It's often referred to as a "failed star" or a "star that never was."