Tools and methods are provided for removing biological units from a body surface utilizing a removal tool. The tool is of a concentric tube configuration comprising first and second elongated bodies, in which the second elongated body can be retracted into the first elongated body. The tool may incorporate retention members and mechanisms configured to impede movement of the biological unit in the direction of a distal end of the tool and to improve retention of the biological unit in the tool. Distal fluid or gas delivery may supplement a vacuum in a luminal space to help extract biological units from surrounding tissue.