No problem! I look forward to seeing what else you put forth! The challenges are a perfect way to hone your skills. 

Ah thx for the hint, didnt know that! Will consider it in the next challenge! Searched for Challenges like that to motivate me for more pixelart :)

Great idea, especially the apple core on the second grid.

Cool piece! I love how you used the core of the apple too

This is a pretty cool one! However, your final piece has 9 colors, technically because the transparency is considered a color. You could use the white as a background color or remove it entirely to make your color count exactly 8, if you wanted.