Earlier this week, news went viral that two white giraffes were spotted in Kenya — a completely white female and her baby giraffe, which had barely visible spots on its skin. Although bright white giraffes aren’t very common, there have been sightings before — and every time a candid white animal is immortalized in a photo, people freak out.

It’s not too hard to imagine why: these creatures look straight from a fairly tale. It's like someone drew them on the landscape and forgot to fill them in with color. It's impossible not to wonder how the animals get their ghostly appearance.

In fact, the reasons vary. The two white giraffes in Kenya — spotted by rangers at the Hirola Conservation Program in early August — have a genetic condition called leucism. Leucism results in the partial loss of color from an animal’s skin, hair, or scales, but not in other organs like the eyes, for instance. Other animals are white because they’re albinos — they have a congenital disorder that inhibits the formation of color in the animal’s skin, hair, scales, and eyes. That’s why leucistic animals can have dark eyes, while albino animals usually have pink eyes. (The pink color is actually from the blood vessels inside the eyes, seen through colorless irises.)

A white leucistic giraffe was spotted in Tanzania’s Tarangire National Park last year, while a ghostly white moose was photographed in Sweden last month. The moose wasn’t an albino either, according to National Geographic, but it had a partial form of leucism called piebald — where only specks of colors remain.

Being bright white in the wild can put the animals at a disadvantage, according to Stephanie Malinich, the collection manager of the Tetrapod Collection at the Museum of Biological Diversity at The Ohio State University. “Coloration is what animals use to survive,” she says. When they’re completely white, animals are easier to spot, attracting predators. Albino animals are also more likely to develop skin cancer, because they’re more sensitive to sunlight, Malinich says.

Here are some photos of a few other unusually white animals.

The albino alligator

One of the most famous residents of the California Academy of Sciences is this completely white Alligator mississippiensis called Claude. The alligator is white because it has albinism. Claude has become a mascot of the city of San Francisco, SFGate says, and just turned 21 on Friday, September 15th. (The museum even threw him a birthday bash.)

The albino Western lowland gorilla

Here’s Snowflake, the only known albino gorilla, who died from skin cancer in 2003, according to National Geographic. The gorilla was born in Equatorial Guinea and taken to the Barcelona Zoo in Spain in 1996. After his death, scientists sequenced his genome from frozen blood and discovered that the genetic mutation responsible for Snowflake’s albinism was likely due to the fact that his parents were related.

The white squirrels of Olney, Illinois

The city of Olney, Illinois is apparently famous for being home to many white, albino squirrels. There are various theories as to why the white squirrels came to Olney, but the town takes them very seriously: the animals have the right-of-way on all streets as well as sidewalks, and their populations are consistently counted to make sure they’re healthy. In 2015, 88 albino squirrels were counted in the Squirrel Count, up from 75 albinos in 2014.

The pearly white snake

This pearly white snake was discovered in Australia this past June and given to authorities at the Territory Wildlife Park in Berry Springs, which posted photos of the snake on its Facebook page. The reptile is native to Australia and usually dark brown in color. But not our friend here! This milky snake is leucistic, lacking all color except in its eyes.

And for the grand finale, here’s a photo of a leucistic peacock found on Wikipedia, with not much of an explanation. The photo is cool, though.