The Yashia goby is a small shrimp goby that forms a symbiotic relationship with a pistol shrimp, and the two live in a small hole, or cave. The shrimp is an excellent digger. It will dig out the burrow and constantly maintain it. However, it has very poor eyesight which makes it vulnerable to predation. The shrimp goby, on the other hand, has excellent vision and will warn the shrimp of any potential dangers. This is accomplished by the shrimp constantly touching the fish with its antenna to determine whether or not the fish is retreating back into the hole.
Below is a video demonstrating this relationship. The shrimp is digging away while the fish is constantly hovering near the mouth of the hole.