Vintage Shell petrol pump and Automobile Association AA sign ephemera at St Mawes tourist attraction, Cornwall, England, UK

Vintage Shell petrol pump ephemera at St Mawes tourist attraction, Cornwall, England, UK

Tree lungwort (Lobaria pulmonaria) growing on Hazel (Corylus avellana) Lungwort is an indicator of air pollution as it only grows in clean air. Sutherland, Scotland

Hokkaido, Japan

Hokkaido, Japan

Paris, France

Okinawa, Japan

Winegrowing, Malbec grape variety, roses are used as indicators for an infestation of the vines by insects, Maipu, Mendoza Province, Argentina, South America

Direction sign in different directions, distance indicator, Cape Forchu, Yarmouth, Nova Scotia, Canada, North America

So-called bath tub rings of Antelope Canyon as seen from Lake Powell, indicators of peak water levels, Page, Navajo Nation Reservation, Arizona, United States of America, USA

Battery empty, battery indicator, battery, iPhone, iOS, smartphone, display, close-up, detail

Aerial view, Graf Bismarck 3, 5, former mine, Schachtzeichen mine indicators on the A2 motorway cover, Schachtzeichen RUHR.2010 art installation, Gelsenkirchen, Ruhrgebiet region, North Rhine-Westphalia, Germany, Europe

German underground hydrant indicator signs on a wall

A car interior, the dashboard, instrument panel, and fuel gauge. A speedometer

A car interior, the dashboard, instrument panel, and fuel gauge. A speedometer.

Weather vane with rooster