Microscopic baby sea urchin crawling with tubed feet is among video winners of Nikon Small World in Motion competition

A small juvenile sea urchin crawling on red algae.

The photographer identified the species as Arbacia lixula — a black sea urchin. As juveniles they show have a distinct reddish coloration compared to the typically black adults. (Image credit: Dr. Alvaro Migotto/Nikon Small World in Motion 2025)

Stunning microscopic footage has captured the moment a translucent baby sea urchin crawled across a bed of red algae. The video earned fifth place in the annual Nikon Small World in Motion competition.

Alvaro Migotto, a zoologist at the University of São Paulo in Brazil, captured the mesmerizing video of the juvenile sea urchin as it moved across its habitat and identified the species as Arbacia lixula — a black sea urchin that is commonly found along the Brazilian coast and throughout the Mediterranean. Migotto discovered the tiny creature while examining debris that had washed ashore near the Center for Marine Biology where he works.

"It was simply by chance. While I was examining various materials — such as algae, pebbles, and seashells washed ashore — under the stereomicroscope in search of other organisms, I unexpectedly came across this tiny sea urchin calmly walking on a piece of red calcareous algae," Migotto told Live Science in an email.

"The scene struck me as perfect — not only was the animal moving naturally over a substrate it typically inhabits in the wild, but the combination of these two elements also created excellent contrast and pleasing colors," he added.