“Seahorse” is the name of a type of fish in the ocean. It comes from the fact that this animal actually resembles a horse that humans see on land. Specifically, this likeness comes from the head and the tail of the seahorse and the land horse that we see being ridden in the old west movies and the various horse farms. They are segmented creatures, with the lines separating the segments clearly visible in the light.
Seahorses have bony armor. Fun fact time. The word “seahorse” can be written in one of three ways and still be grammatically correct, no matter what the context. One way to write is one word - “seahorse”. The second way is to write it as two words - “sea horse”. Finally, one can write it hyphenated - “sea-horse”.