Word for updating one single "square" in a grid

What would be an appropriate word for updating one single square in a grid/matrix, e.g. in a game of Tetris?
What are those squares called?

I was hoping for something like "Update square."

How about Updating Cell or Updating Unit?

Each individual part of a matrix is called an element. Pixel can work fine, if you feel like using an analogy with an image (pixel was initially short for picture element).

I have always heard these terms used:

• an element of an array,
• an entry (or an element) of a matrix,
• a cell of a grid.

P.S. The following is not really a language issue, but if you're doing image processing, you should be aware that A Pixel is Not a Little Square!