An unusual bloom in Polish forests. Be careful when walking your dog.

Foam bloom is an intriguing organism found almost everywhere in the world. In Poland, it appears in late spring and can be found until autumn. Historically classified as a fungus, it is now classified in a different kingdom – protists. The terms variegated bloom and variable bloom are also used interchangeably. A more interesting name is "witch's butter," which the bloom owes to its characteristic, light color – ranging from bright yellow to brown. Foam bloom grows on rotting leaves, tree trunks, and soil.

The plasmodium (a multinucleate mass capable of amoeboid movement on the substrate) of the foam bloom moves on the substrate using pseudopods in search of nutrients. It does not require light and develops in darkness. It crawls out to illuminated areas during spore production.

Foamy bloom. Incredible zinc tolerance.

Another interesting feature of the creature is its high tolerance to heavy metals, such as zinc. Because of this property, the bloom is being studied for its potential use in medicine.

In the past, this slime mold evoked negative emotions. References to "witch" appeared in many European regions – Germania, Latvia, and the Netherlands. According to Finnish legends, witches used the bloom to spoil their neighbors' milk. In Scandinavia, the term "bjära's vomit" was used instead of "witch's butter" (bjära is a familiar belonging to a witch and used to steal milk, and can take the form of a cat or rabbit, for example).

"Witch Butter." A Health Threat to Dogs

Despite its negative connotations, the foamy mold doesn't pose a significant threat to human life or health – contact with it can result in an allergic reaction. It poses a greater threat to dogs, which may experience stomach upset, diarrhea, nausea, or vomiting after licking or ingesting it. When walking in the woods with your dog, it's worth keeping an eye out for the presence of the slime mold and steer in a different direction.

Read also: Mushroom pickers, get your baskets ready – the forest harvest is coming. Here are some tips straight from the forest. Read also: Poland is a mushroom empire. Nearly 700 million złoty straight from the forest.