Many studies have reported the arrival and subsequent range expansion of foreign species within the marine ecosystems, but few studies have documented species that arrive and fail to establish. In 2000, the sea anemone Sagartia elegans (Dalyell, 1848) was first found in Salem, MA and persisted seasonally until the winter of 2010-2011 after which it has not been found. In both laboratory and field based temperature growth studies, S. elegans began regressing in size at 11 °C, stopped asexually reproducing at 9 °C, and died by 4 °C; these temperatures are far above the average winter sea surface temperature in the Gulf of Maine, therefore suggesting that S. elegans requires a warm-water refuge. It is still unknown as to what caused the population collapse, but it is likely a combination of both a lack of genetic diversity and an inability to tolerate the cold temperatures during winter.