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!
Shrimpfireurchin