aculei
/əˈkjuːliaɪ/
noun
- Sharp, pointed structures such as spines or prickles on plants or animals.
- Under the microscope, the aculei of the sea urchin appeared like tiny needles.
- The botanist noted the arrangement of aculei along the stem of the rose.
- The aculei on the cactus protect it from being eaten by animals.