800×
Underwater Fruit Punch
Look at this black-and-white image — I wonder what the object that looks like a slice of fruit might be?
The hint is in the title!
400×
Let's decrease the magnification a little.
There are more objects that look like slices of citrus fruit.
100×
Continue decreasing the magnification and...wait a moment!
There are still lots of fruit slices, but they seem to be attached to something like a branch.
40×
Let's try decreasing the magnification even more.
Looks like the fruit slices are growing along branches.
Answer: Diatoms
The objects pictured, which resemble tasty slices of fruit, are actually single-celled algae called "diatoms."
Diatoms live in a wide range of habitats, from freshwater to seawater (the electron microscopy image shows diatoms attached to seaweed), and are an important food source for fish. When present in large numbers, they can cause red tides.