Hermit Crab Association

http://www.hermit-crabs.com/

Ghost Crabs - my Note    info1    info2    info3 (feeding on a dead fish)    painted ghost crab
Ghost Crab Eyes -
  It has large black eyes that are supported on stalks. Its eyes help it see in any direction. There are horns attached to the end of the eyes of male crabs. It is by these horns that the gender of a crab is recognized. The eyes of these creatures are sensitive to changes in light.  http://www.animalspot.net/ghost-crab-sand-crab.html

Hermit crab
  http://www.wisegeek.com/what-are-hermit-crabs.htm

side note - Google: helmet shell species  will give seashells or sea snail animals of Family Cassidae.   info1   wiki