Abstract: A container may include an envelope made of flexible material, wherein the envelope includes lower and upper ends, and wherein the envelope is closed at least at the lower end. The envelope may include: opposite first walls, each having an edge at the lower end; a base at the lower end, configured to rest upon a support surface; and a pair of additional walls between the first walls, wherein each additional wall is joined to the first walls via a pair of additional edges, and wherein each additional wall has a lower folding zone at the base. Each edge may be defined by a heat seal formed between a first wall and the base. The base may be formed with a shape that defines a concavity designed to face the support surface. The base may include a pair of half-parts separated by a central fold to define the concavity.