Brook floaters have yellowish or greenish shells. As juveniles, the shells are covered with dark green rays. The outer surface becomes brownish with rays partially obscured or almost black in adults. The inner shell surface is a bluish white, often with salmon, pink or purple in the beak cavity.

The brook floater depends on streams with clean, flowing water and substrate that they can anchor into while filter feeding. Their habitat is vulnerable to pollution, development, invasive species invasive species
An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars.

Learn more about invasive species , and changes in temperature and precipitation patterns resulting from climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Learn more about climate change .

The brook floater has an elliptical-shaped shell that grows to a maximum length of about 3 inches, or 75mm – no bigger than a credit card.

The brook floater depends on streams with clean, flowing water and substrate that they can anchor into while filter feeding. Evidence suggests they are sensitive to high water flows that can dislodge them from stream bottoms. Their habitat is vulnerable to pollution, development, invasive species invasive species
An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars.

Learn more about invasive species , and changes in temperature and precipitation patterns resulting from climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Learn more about climate change .

The brook floater is a long-term brooder, which means it undergoes fertilization in the summer and holds onto its larvae -- called glochidia -- until the following spring or summer. After the glochidia are released, they use hook-like appendages to latch onto the gills, body, or fins of fish. The glochidia take in nutrients from their unassuming hosts until they metamorphize into juvenile mussels, and drop off onto the stream bottom to mature. 

When removed from the water, they have a peculiar habit of gaping their shell open to expose their orange “foot,” giving the appearance that they are sticking out their tongue.