This tiny shrimp was found on this blue tunicate in Manado, Indonesia. The flattened shape suggests it could be a Cryptic Sponge Shrimp (Gelastocaris paronae), but as far as I'm aware G. paronae is found on sponges where it's colour and patterns almost completely camouflage it. This shrimp is mostly transparent, so perhaps it's a juvenile.
Have you seen something similar or can you identify the species?