Trematode -

: A tough, continuous outer layer called a syncytial tegument protects them from the host's digestive enzymes and immune system.

: They typically have flattened, leaf-like, or worm-like bodies ranging from 1 mm to several centimeters in length. trematode

Schistosomes and Other Trematodes - Medical Microbiology - NCBI : A tough, continuous outer layer called a