Question

how would pili be important to colonial bacteria?

Answer 1

Lets work through the problem together - do you know about what pili are or what they do?

Answer 2

A pilus (a single form - pili is plural) is like a long thin straw or tube that sticks out of the membrane of a bacteria.

Answer 3

Here is a picture, copied shamelessly from Wikipedia. Does it make the idea of what a pilus is and what it does clearer, I hope?