Xenophyophores, the world’s largest single-celled organisms, grow up to eight inches in diameter. More than 42 species have been discovered in deep parts of the oceans.
When they were discovered in 1889, they were believed to be sponges. They grow in a variety of shapes and colors and do resemble sponges in appearance. Xenophyophores live in every ocean and have been found in waters nearly seven miles deep.
Their preferred habitat are the abyssal plains, where they constantly dig in the ocean bottom for food. They feed by engulfing their prey, similar to an amoeba. For this reason, they were long thought to be amoebae, but genetic studies place them as a specialized group of Foraminifera.
Many other animals seem to depend on xenophyophores for habitat creation. Isopods are often found living where xenophyophores have recently dug and brittle stars are often found sitting on top of or underneath the xenophyophores.
Very little is known for certain about the life cycle of xenophyophores. Their fragility makes it difficult to harvest them for captive study. While they are abundant on the deep ocean floor, they are not found in any other habitat.