When you think of sponges, you may think of the synthetic ones for washing dishes.

Natural sponges are primitive animals that may seem immobile, but photos from a recent Arctic expedition show that slowly but surely they make tracks on the seafloor as they move. Synopsis: Sponges are used in most households, but they are simply imitations of natural sponges that have been used for thousands of years for cleaning and bathing. Perhaps future expeditions will help us understand these and other hidden talents of sponges. But this is a key part of science: looking for one thing and finding something else altogether new.

Why and how they do it is still a mystery. Sponges have no muscles or apparent method of mobility. Most of them had left tracks in the mud behind them, filled with protein crystals called spicules. The sponges were scuttling-very slowly-across the sea floor. They set up specialized photography to look at vent activity but were amazed to see something else. Scientists studying undersea vents in one of the least hospitable places on Earth, in the cold blackness a mile beneath Arctic ice, found thousands of sponges living in the warmer water near the thermal vents. But that changed when it was revealed that sponges could move. Sponges were thought to be unresponsive to outside stimuli and, well, very plantlike. Today there are 6,000 known species and new ones being identified regularly.

Sponges evolved more than 500 million years ago, flourished through Earth’s great extinction events, and have endured ever since. But new accidental findings may show we’ve underestimated them. They’re also the least evolutionarily advanced creatures on the planet. Sponges may look like plants, but they’re animals-some of the longest-lived on Earth, with a few living more than 10,000 years. Or are sponges able to move faster sporadically? Credit: AWI OFOBS team, PS101 With paces of just millimeters per year, some tracks may have taken hundreds of years or more to create. Sponge-spicule trails are typically tan and may move uphill and change directions like this one.

Can sea sponges move