Odontodactylus havanensis like/need to burrow. It should have a substrate of sand and large gravel (pieces of LR and shell 1/4 - 3/4 inch) about 3 inches deep. Place a piece of flat LR on top. The animal will dig a burrow under the rock eventually ending up with a u-shaped burrow. Usually they will eventually bury the surface rock, so don't use one with valuable corals, etc.
O. havanensis are some of the most interactive and interesting stomatopods available, but they are not the easiest animal to keep. They can jump at least 4 inches out of the water, do not tolerate rapid temperature and salinity swings, and most importantly, do not survive periods of low oxygen.
One of the more fascinating things about them is their polarized signaling system. Look at the pink uropods and antennal scales with a pair of polarized sunglasses and you will see that as you rotate the plane of polarization, the color will change. These signals are used in species and sex recognition.
Enjoy!
Roy