When you think of sea needles, you might first think of the spiny and elongated structures that stick out from some types of sea urchins. However, there are several other synonyms for this term, depending on the context. For example, some people might use the term "sea pickles" to refer to similar protrusions on certain types of jellyfish. Alternatively, you might use the term "sea thorns" to describe the sharp, pointed structures on certain types of coral or rock formations. Overall, while "sea needle" might be the most common synonym for these sorts of structures, there are plenty of other ways to describe them depending on what you're looking at.