One of the bulldozer shrimp, these maintain burrows in the sand used by themselves and their lookout shrimp gobies. When out of the hole, the shrimp keeps one of its long antennae on the goby, and quickly retreats to safety if the goby suddenly dives into the hole.
The goby in the next few photos is Cryptocentrus fasciatus.
The lookout goby in the photo below is Amblyeleotris periophthalma.
Created 25 October 2021