Much like a cell , a virus is able to

Similarly to cells, viruses can spread and grow, as well as mutate. They can change what they do becoming even more deadly or they can become immune to medicine. They can also spread from cell to cell, then from people to people, change the way they spread as they mutate, and many many other things that are usually bad for humans.

Spherical shaped cell might increase the surface area and decrease the volume.

The answer would be sand and gravel