Ghost crabs (Ocypode quadrata) live in U-shaped burrows doing God knows what during the day, but they emerge at night to feed on all sorts of detritus washed up by the surf. But they also apparently go after sand fleas, mole crabs (Emerita talpoida), and even cute, defenseless, newly hatched birds (e.g., sooty terns). And plover eggs, on occasion. But they hate fireflies for some reason. The stalked eyes are noteworthy, especially if you harass them enough to get them to fold down into the lateral grooves on their carapace (nice trick!). Photograph taken in Mantoloking, NJ (USA).