How do I refer to previous object?

Hello!

So I do create Pixel sprites at Blue dot. Than from Pixel creates line. From Blue dot to the Green dot. Red line constantly moves. So how do I get green dot coordinates?

I tried to refer like Pixel(1).X - like last created object.

I tried to creat counter - TileCount. If Pixel indexes goes otherway. But it's not working

Small addition. Yes, I do know speed of the red line and can refer to it straightforard, but it's to complex for my project

It's Pixel(-1).X , right? -__-

Where I can read more