Outer space, or underwater?
This cluster of cells is a chain of diatoms (glass-like phytoplankton) called Asterionella. They get their name from the distinct star shape of the linked chains. Asterionella is one of more than 25 different kinds of phytoplankton that the Exploratorium Living Systems lab staff might spot in a single water sample collected here at Pier 15 during the Spring Bloom.

This work is part of the Ocean Observatory Project, funded by the Gordon and Betty Moore Foundation.