olm; Proteus anguinus
A cave-dwelling aquatic salamander native to Europe. The word is usually written in katakana.
The olm is a rare amphibian that lives in caves.
Katakana spelling is standard for this animal name; the kanji form 洞井守 is rare and not commonly used.
Ateji kanji spelling; very rarely used and may not be recognized by most readers.
The name ホライモリ is likely a combination of 洞 (hora, 'cave') and 井守 (imori, 'newt'), referring to its cave-dwelling nature and salamander-like appearance. The exact origin is uncertain.