Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Sentence1: Flatworms Flatworms or Platyhelminthes include flukes, tapeworms, and turbellarians. 
Sentence2: Tapeworms belong to the phylum Platyhelminthes.
tapeworms

Sentence1: Veins generally carry deoxygenated blood. 
Sentence2: Blood carries blood cells.
blood

Sentence1: Sponges are filter feeders. 
Sentence2: Sponges eat krill and plankton.

Sponges