Possible Clues:

• It doubles in division
• Microscopic one-celled protozoan
• Microscopic, single-cell creature
• Are diamonds out of fashion with bachelor leading a simple life?
• Bio 101 study
• Unicellular form
• Bloblike organism
• Creature with pseudopodia
• Blob on a microscope slide
• O, Mam, be a one-celled animal