11. The bright dots you see when you look up at the sky are your white blood cells.
Dubbed the “blue field entoptic phenomenon” or “Scheerer’s phenomenon”, this is the appearance of tiny bright dots moving across one’s visual field when one looks up at the sky. They are visible only for a second or less. These dots are the result of white blood cells moving in the capillaries in front of the retina. The red blood cells absorb the blue light, while the much rarer white blood cells do not, leaving gaps in the blood column which produce the bright dots.(source)
12. Some tumors contain hair, teeth, and bones in them.
These tumors, called “teratoma”, contain components of tissues and organs. Doctors have found not only hair, teeth, and bones in teratomas but fingers and even partially formed humans have been discovered in some severe cases. They are thought to be a congenital defect and are very rare, with some of them not being spotted until later in life.(source)
13. Viruses can get viruses.
This is quite the “hunter becomes the hunted” situation. A giant virus called the “mamavirus” was identified, which, upon inspection, was found to have smaller viruses attached to it. These caused the mamavirus to grow abnormally while, at the same time, inhibited its ability to replicate. The smaller virus has been dubbed the “virophage”, owing to its resemblance to bacteria-targeting viruses called “bacteriophages”.(source)
14. Giant tarantulas keep tiny frogs as pets. The tarantula protects the frog from predators, and the frogs, in turn, eats the insects that could possibly harm the tarantula’s eggs.
The dotted humming frog and the burrowing tarantula have quite a mutually beneficial relationship. What makes this even more remarkable is the spider, owing to its size, could very easily kill and consume the tiny frogs. These frogs feed on the insects that are attracted by the remains of the tarantula’s prey. The frogs also remain protected from predators like snakes due to the presence of the massive spider in the vicinity. The spider, on the other hand, is benefitted by the presence of the frogs, which specialize in eating ants, one of the major predators of the spider’s eggs.(source)
15. A lobster’s brain is located in its throat, its nervous system in its abdomen, its teeth in its stomach, and its kidneys in its head.
A lobster also uses its legs to hear, its feet to taste, and has the tendency to favor one front limb, indicating that they could be right- or left-clawed.(source)