In February 2010, a similar specimen with a total length of 14 cm (5.5 in) was caught 305 km (190 mi) off the coast of Louisiana, in the Gulf of Mexico.

From the one finding of the pocket shark in the Gulf of Mexico (M. mississippiensis), the mouth was described to have a rectangular-like opening on the underside of the body.

The juvenile male shark found in the Gulf of Mexico weighed 14.6 g (0.51 oz) and had a total length of 142 mm (5.6 in).

The overall shape of the shark is cylindrical, with a wide, rounded snout tapering back toward the caudal fin.

The closest suggestion for the purpose of this gland is to act as a luminous pouch as found on the species Euprotomicroides zantedeschia.