Assertion: gastropod's foot | /r/ObjectUse | used for creeping
Facets:
Source sentences:
text: Giribet and colleagues concluded, in 2006, the repetition of gills and of the foot's retractor muscles were later developments, while in 2007, Sigwart concluded the ancestral mollusc was metameric, and it had a foot used for creeping and a "shell" that was mineralized.