The microscopic particle that invades a cell and often destroys it is called a virus.

Here's why:

* Viruses are not living organisms: They lack the machinery to reproduce on their own.

* They invade cells: They inject their genetic material (DNA or RNA) into a host cell.

* They hijack cellular machinery: They force the host cell to produce more viruses, leading to cell death.

While other microscopic particles like bacteria can also cause harm to cells, viruses are specifically known for their ability to invade and destroy cells from within.