Sacoglossan sea slugs (Mollusca: Opisthobranchia) are one of the few groups of specialist herbivores in the marine environment. Sacoglossans feed suctorially on the cell sap of macroalgae. from which they "steal" chloroplasts (kleptoplasty) and deterrent substances (kleptochemistry). retaining intracellularly both host plastids and chemicals. https://www.roneverhart.com/Hermit-Crab-Ornament/