1) Small thorn 
Spinules are small spines or thorns (vertebral columns) that are part of biological and manmade structures. The word originates from the Latin word spinula and is often used in botany and zoology. The presence or absence of spinules, and their shape, can differentiate species and is used to describe and distinguish anatomical features. The develop...
a small spine
• (n.) A minute spine.
minute spine, often broadened at base.
Spin'ule noun [ Latin spinula , dim. of spina a spine: confer French spinule .] A minute spine. Dana. 
A little or weak spine.
A minute spine.
a small spine
spinule A small spine.