motile

"It is also a hard fungus to keep track of because they have a life stage where they're motile, they have a flagellus, which resembles a sperm tail, and they swim around," Stajich said.

The bank guarantees a vial will have 10 million or 15 million total motile sperm.

Yilingia, Dr. Xiao noted, “is neither the oldest segmented animal nor the oldest motile animal, but it is thus far the oldest known segmented and motile animal capable of producing long and continuous trails.”

These amoebozoans—a phylum of single-celled eukaryotes—spend most of their lives as individual organisms, but will gather into motile multicellular formations to search for food and reproduce.

The reconstitution of each element of these motile groups, no matter how detailed, will never explain why groups move in the direction of the gradient but individual elements do not.