infrequently Lysoquilla maculata appear on shipping lists, they need very different conditions than almost any other marine critter you'd think to keep, a sandbed at least 3" deeper than the beast is long, and no rockwork at all, anything heavy on the surface can collapse their burrows trapping them or crushing them.
I had a big guy that passed on when he was a little over 10" I only saw his whole body when I put him in his 20, and when he died, other than that I had a pet hole that exploded for a fraction of a half a second once a week when I dropped a feeder in.
Very interesting critter but not a visually stimulating aquarium. I had a lot of people asking my why I had a tank full of sand with nothing in it. On special occasions you'd see 2 gold eyes peering out at you, but as soon as he knew you were looking he'd drop straight back into his burrow, and that'd be it. My understanding is that all spearers follow this same general MO, but I've only kept the one species personally.
I honestly found that the best stomatopods for aquariums are the big smashers, they're tough as nails, eat literally anything, and are scary smart for a heavily armed crustacean. I also had a G. chiragra I kept in a tank with a big condy anemone, the chiragra learned to steal krill out of the anemones tentacles, and built a staircase out of liverock rubble to reach them easier.
If you haven't seen Roy Caldwell's stomatopod site it's a good place to learn a bit about some of the more common species-
http://www.ucmp.berkeley.edu/arthro.../eumalacostraca/royslist/index.html#directory