nephridium
/nɪˈfrɪdiəm/
noun
- An excretory organ in many invertebrates, such as worms and mollusks, that functions like a kidney.
- In some mollusks, the nephridium also helps regulate salt balance.
- Each segment of an earthworm contains a pair of nephridia.
- The nephridium filters waste from the body fluid and releases it outside.