UMUR "Mutaation aiheuttama sisäinen mätäneminen" ("Internal Rotting Caused by Mutation") is the first demo recording by Finnish death-doom metal act Rippikoulu. The demo was independently released in 1992. Rippikoulu formed in 1990 and disbanded in 1995 after releasing two influential death-doom metal demos.

It´s not only the title of the demo which is in Finnish. It´s also the songtitles and the lyrics, but it´s the kind of release where it doesn´t matter much because even if you could understand the Finnish language, I´m not sure you´d pick up many of the words sung here. The vocals are unintelligble brutal growling. The music is gloomy, raw, and ultra heavy old school death metal, which at times is so slow that labelling it death-doom metal isn´t all wrong. It´s not doomy all the time time, and Rippikoulu also play some pretty fast-paced death metal parts (listen to "Pimeyden kirous" ("Curse of Darkness") and "Maailma palaa" ("The World is Burning") to hear that).

The arcane and gloomy atmosphere of the demo are the greatest assets of this recording, because the songwriting isn´t particularly memorable and the tracks are also a bit hard to tell apart. The musicianship is pretty strong and the sound production is decent sounding too considering that this is a demo recording. A 3 star (60%) rating is warranted.