An hourglass with sand flowing through it. 

Hourglass

A sand clock or hourglass for keeping time.

Sand Clock Or Hourglass

Envelope attached to the string of a floating balloon.

An hourglass icon with sand in the bottom.

Abstract landscape with clouds, mountains or pyramids, and sand dunes or uneven ground.

A busy and overworked manager or employee surrounded by charts, graphs, and notifications.

An hourglass with sand pouring inside the container.