This sea anemone is found in the shallow brackish water of coastal lagoons and salt marshes where its slender column is usually buried in the mud and its tentacles exposed.

Its genome has been sequenced and it is cultivated in the laboratory as a model organism, but the IUCN has listed it as being a "Vulnerable species" in the wild.

[4] The starlet sea anemone has a bulbous basal end and a contracting column that ranges in length from less than 2 to 6 cm (0.8 to 2.4 in).

The outer surface of the column has a loose covering of mucus to which particles of sediment tend to adhere.

Plants in its habitat include foxtail stonewort, Lamprothamniun papulosum, green algae Chaetomorpha spp., and ditch grass (Ruppia) spp.

The spherical planula larvae that hatch about two days later spend around a week in the water column before settling on the sediment and undergoing metamorphosis into juveniles.

[8] On the west coast of the United States, all individuals are also female while in Nova Scotia, all are male, and reproduction in both these populations is likely to be by asexual means.

[7] It is easy to care for in the laboratory, even in inland locations, and a protocol has been developed for the induction of gametogenesis which can yield large numbers of embryos on a daily basis.