A method and tube for separating a sample. The tube is configured to separate agglomerated or clumped material or other sample components having over a particular size from other smaller size portions of the sample. For example, blood clots may be separated from serum of a blood sample. The tube includes a chamber with a closed bottom and a sidewall extending upwardly from the bottom, and a sample inlet branch coupled to the chamber. A slit is positioned between the chamber and the sample inlet branch so that after a sample is placed into the sample inlet branch, a portion of the sample having a size smaller than the slit (e.g., liquid material) passes through the slit and into the chamber, and material in the sample having a size larger than the slit remains in the sample inlet branch.