Bioconvection
The pattern photographed below is due to bioconvection of a bacterium called Bacillus subtilis. This pattern is a one-dimensional wave pattern, which appears in the meniscus created by the agar plate shown on the figure. The insert shows how the pattern intensity varies along the white line drawn on the figure.
The bacteria live in the surrounding fluid, which is also a source of nutrients.
From N. Mendelson & J.L., J. Bact. 180, 3285-3294 (1998).