Abstract: A test tube may include: an annular body having an open first end, a closed second end, a longitudinal surface extending between the open first end and the closed second end and enveloping a hollow interior of the annular body and a central longitudinal axis; wherein the longitudinal surface of the annular body may include: a first longitudinal portion that may include the open first end of the annular body and having a substantially circular cross-section; and a second longitudinal portion that may include: a first longitudinal side having a substantially circular-arc cross-section; and a second longitudinal side tapering in a longitudinal direction of the annular body towards the closed second end of the annular body.

Abstract: A test tube including an annular body having an open proximal end and a closed distal end, and an longitudinal member in a distal portion of an interior of the annular body, the longitudinal member is substantially parallel to a central longitudinal axis of the annular body and is connected to an internal surface of the distal portion of the annular body.