Serpent stars!

One of the unexpected delights of keeping a marine reef tank is that the addition of new corals often brings accidental introductions of larvae or eggs of other species. The most common of these are small, white cushion stars and brownish glass anemones (Aiptasia sp.) Neither of these are particularly attractive or welcome and we remove them whenever we can. Probably the worst interlopers are Pistol Shrimps and Mantis Shrimps, both of which can allegedly shatter the glass of the tank with their chelae !

Whenever I carry out a weekly routine water change (as I did today) the drop in temperature seems to irritate other unintended residents: Serpent Stars. I don't think these are harmful, so won't remove them unless they grow really large or too abundant: fascinating creatures to watch!