This is a story related achievement. In Chapter 14, you have to find these Roseatta samples which look like ice cubes containing alien parts. Once you have collected all of the Roseatta samples, you will have to return to the lab, starting up Chapter 15. You must then rearrange the Roseatta samples (the blocks) into a correct order that ultimately forms an alien. You can work out the order by trial and error, but it is relatively easy to see how the pieces go together because of where the slices occur along the aliens body. Once you have the correct order, the pieces will automatically merge and you will get the achievement. I take no credit for the video below, so take a look at it if you are having any trouble or prefer visuals over text. Message me if you have any questions or concerns.
*Credit to achievement hunter for the video