If you look close enough, you can just see them squeezing their way in between grains of sand and scooting along on seaweed—tiny flatworms. When scientists looked closer at these tiny creatures, they found that one species was actually four.
The grips on your gumboots give way under foot as a slippery blade of seaweed threatens to plunge you off the rocky shoreline into the cold waters of the Pacific. But what kind of seaweed is to blame? Now, a new phone app can help you find out!