How LLMs hallucinate a seahorse emoji due to training data patterns
Large language models consistently claim that a seahorse emoji exists, even though no such emoji has ever been part of the Unicode standard. Theia Vogel reports on her website about this peculiar behavior and its technical causes. When asked about the existence of a seahorse emoji, models like GPT-5, Claude Sonnet 4.5, and Gemini 2.5 …