High-magnification cross section of an aloe plant
Aloe has been used for thousands of years—tracing all the way back to Egypt 6,000 years ago—to heal wounds and burns. This particular micrograph shows cells from Aloe erinacea, an aloe plant native to Namibia that is endangered due to habitat loss. Large, blue cells in the center are called xylem: they conduct water from the roots to the leaves. The small, circular clusters of cells are called phloem: they transport food made by the leaves to the rest of the plant.
Image by Anatoly Mikhaltsov.
The tentacles of a box jellyfish (Chironex fleckeri) trail behind it and can reach 15 feet (4.6 meters) in length. Found in northern Australia and adjacent waters, a sting from this species can be deadly. This species of box jellyfish, the largest, can have as many as 60 tentacles.
Photograph by David Doubilet, National Geographic.