Good suggestions, I have considered inverts but decided to go with a fish and here's why. I did some research on sand sifting stars when I first started my tank and most report that they often starve in the aquarium. Without having a dsb
and having a smaller tank they tend to run out of food quickly. I have also considered conch as they are cool (and tasty, not out of an aquarium however) but I decided against them because I want something to add some character that I can actually see. I do have a bunch of nassarius snails and they only pop out when I feed then they are gone again within minutes. I have considered a goby/shrimp pair but do they not tend to hide out at the burrow?