Even if someone pointed out that there was a pygmy seahorse on a piece of coral, you likely would not see it. Only the size of a paper clip, these tiny fish look like their larger seahorse cousins, but are incredibly small. They adapt to their environment with camouflage coloration. They have only one gill slit and do not have a brood pouch like the seahorse, but otherwise look like a miniature version. Since these pygmies are difficult to spot, cataloging these creatures requires a great deal of cooperation among observers.
Read how scientist use social media to collect data on these creatures: https://www.atlasobscura.com/articles/taiwan-pygmy-seahorses-social-media