Rangu (Rank?)
Reportedly a name related to haymaking, a stack/stook of stale or musty hay (not conclusive, despite its being named in 2000*). Viires translates rank as trough (W. Est. dialect), but ranga seems a more common genitive; Forssmann gives rank:ranga as boulder, rock or obstacle; Wiedemann rank:rangi, also trough, or row (of plants), or cross-references rank:ranga to ränk which doesn’t get us very far either, and not a genitive -u in sight. The only one found is rank:rangu for ‘ridge or ‘rocky bank’, It’s also Muhu dialect for fly, which we can probably disregard. Unresolved. Mini hay-related group? Maybe.. See Saadu.
* A possible example of Hamilton’s 4th Law, where very recent naming may borrow terms which might have existed prior to written record if not usage ;o)