heres mine,
hes a bit over 5 years old, i usually feed him pellets but also toss in chunks of shrimp or whatever i have around, i also use him to clean up my xenia lol, out of the tens of thousands ive spent everyone loves the crab the most, i had him in a 67g tank for the last couple years, hes is now in a 50g section of a sump and is soon gonna be moved to a giant sandbed tank which will probably be in the 77-120g range, hes the best sandbed mixer ever.
ive tried keeping things with him over the years but they dont last long, the only thing he didnt bother chasing were cromis but i was scared he would eventually get them at night while they hid in the rocks,hes about the size of a softball and i actually have alot of trouble finding shells but hes done growing now i think he hasnt really grown in the last 2 years