Engineer gobies. While not a true goby they are my favorite. They make such cool tunnels and they get MASSIVE. I lost mine two weeks ago, he was almost 11 (that we know of, who knows how old he really was). He was nearly 14” long and lived in my biocube 32 led. He never bothered anyone. This video is years old but it’s the only one I have where you can actually see him.
This guy made it through several moves and tank disasters (cracking) and just kept on trucking.