Amyone know what this is

[Smacks21294]

Found several in a filter sock. No sign of them in tank. I have a magnificent fairy wrasse that is probably eating them in tank. I'm thinking some type of flat worm bit they look slightly different to all the pictures I see online.

 

[ISpeakForTheSeas]

Elysia flava or E. obtusa - harmless/beneficial Sacoglossan slugs. They're herbivores, with E. obtusa known to feed on Bryopsis, while E. Flava is thought to feed on Cladophora. As mentioned below, I don't know if these are required feeds or just strongly preferred feeds:

Some lettuce slugs (typically from the genus Elysia) will eat nuisance algae species, but their wild diet varies pretty drastically from one species to another, and some species have some pretty specific wild diets (I don’t know if these are required diets or preferred diets, but Reef Cleaners reports that they'll eat just about any green, fleshy algae). That said, Elysia slugs generally feed on siphonalean algae such as Caulerpa, Codium, Acetabularia, Halimeda, Udotea, Byropsis, and Valonia spp. So, in theory, these guys should eat nuisance algae that pops up in your tank.

 

[Smacks21294]

Thanks. Had my fingers crossed