Ramshorn Snail

The term ramshorn snail is used in the aquarium trade to describe any kind of snail whose shell spiral forms tight whorls. Such shells resemble a coil of rope, or (as the name suggests) a ram’s horn.
Most of these snails are of the family Planorbidae. Their blood–like human blood–contains hemoglobin, which may lend these snails a bright reddish color. These ramshorn snails breathe air. Although most are extremely small, some may reach a size of two and a half centimeters (one inch). The shells range from translucent through various shades of brown to a dark, nearly black color. The dark color appears to originate from dietary materials not generally available in the home aquarium, although many varieties from ponds will be this dark shade.