Single-celled wonder (Image: Andy Gooday)

Zoologger is our weekly column highlighting extraordinary animals – and occasionally other organisms – from around the world.

Species name: Syringammina fragilissima

Habitat: The sea floor around Europe and north Africa.


In the late summer of 1882, a ship called the Triton cruised the chilly seas north of Scotland. As it went, it dredged the sea bed for specimens of unknown creatures, under the guidance of the oceanographer John Murray.

Two of the specimens were strange enough that Murray sent them to his colleague Henry Brady for examination. They were chunks of sand a few centimetres across, lightly cemented together and filled with a network of hollow branching tubes.

The samples were fragile and had been badly broken, but Brady was able to identify them as a new species, which he called Syringammina fragilissima: “very fragile sand pipe”. A better name would have been very fragile sand beach ball, but Brady didn’t see the organism underwater.

It turns out that Murray and Brady had discovered the first specimen of an entirely new group of organisms, the single-celled xenophyophores. Shunning the convention that single cells are microscopic, Syringammina is a brute, growing to a width of 10 centimetres – and sometimes even twice that.

Crusty and slimy

The cell branches and splits into hundreds of tubes, which ramify and interconnect in a hugely complex network. It also bends the single-cell convention of having only a single nucleus: Syringammina has many, scattered throughout the tubes.

As the cell proliferates, it builds up a crusty structure around itself, called the test – this is what Murray’s expedition found. To build it, the cell secretes a slimy organic cement, which it uses to stick together tiny particles of sediment.

The tests made by Syringammina are by far the largest structures created by any single cell. The actual cell may not be as big – as the test gets ever larger, the cell will abandon parts of it, which may be taken over by a range of tiny animals, such as nematodes.

A study of a similar species, which was observed through a time-lapse camera for eight months, showed that the creature built itself up in fits and starts: it would grow for a few days, then remain the same size for a few months, then have another growth spurt. Syringammina may do the same thing; we don’t know.

Known unknowns

In fact, there is very little about the monstrous beach ball cell that we do know.

Let us count the ways. We do not know how it reproduces. The group it belongs to, the xenophyophores, is part of a much larger group called the foraminiferans, and these often switch between sexual and asexual reproduction. Syringammina may well do the same thing.

We do not know how it feeds. It may be a suspension feeder, pumping water through its body and sifting out tiny particles of food, or it may poke out a “limb” to pick up food from the sea bed.

Farm animal

Another possibility has been put forward by Ole Tendal of the Zoological Museum of the University of Copenhagen, Denmark: Syringammina may farm bacteria.

Within the tubes of the test, Syringammina accumulates particles of waste, which it stitches together into long strings. Syringammina might use these strings to cultivate bacteria. The waste pellets would provide food for the bacteria, which the Syringammina could then eat.

There is some tentative evidence to support this. A 2004 study found that Syringammina contains unusually high levels of certain fatty acids that are characteristic of bacteria.

One more mystery. Scattered throughout the Syringammina cell – and indeed through the cells of all xenophyophores – are tiny crystals of barium sulphate. They could be a waste product, or ballast, or something altogether different. We have no idea.