- Life cycle stage of digeneans
- Infective stage to 2nd intermediate host (or definitive host in schistosomes)
- Develop from rediae or sporocysts (depending on sp.), inside snail
- Usually, a free-swimming stage
- Most have a tail
- Has a mouth surrounded by an oral sucker, a muscular pharynx and a forked intestine
- Penetration glands present on either side of oesophagus
