Sea star (Komodo, Indonesia)
Coleman shrimp living in fire urchin (Raja Ampat, Indonesia). Fire urchins get their name both from their colorful appearance and from the fact that each blue spine tip has a venom that - if touched/bumped - burns like fire. I can personally attest to the latter, having accidentally bumped one and having about 50 spines penetrate the wetsuit over my calf. Ouch!
Pakistani (aka "banded") Butterflyfish, roughly the size of a dinner plate. (Maldives, Indian Ocean)