Though they look menacing, horseshoe crabs do not bite or sting. The tail, which may look dangerous, is actually used to help right the animal should it get flipped over by a wave, the United States Fish & Wildlife Service explained in a recent Facebook post.
You can help the crab out by gently picking it up by the sides of its shell (not by its tail) and calmly guiding it back toward the water.
"It's a nice thing to do," Danielle Brigida explained in the FWS video after an overturned (and frankly dead-looking) horseshoe crab was righted and scurried back into the surf.
The horseshoe crab, which has been around for hundreds of millions of years, is a unique type of organism known as a living fossil. Though it looks like (and shares a name with) a crab, it's actually more closely related to spiders and scorpions.
In the United States, horseshoe crabs are found up and down the Eastern Seaboard. They snack on worms, clams and algae, according to the National Wildlife Foundation, and can grow to be nearly 20 inches long.