An immense mass of limestone, very compact and of gray color, the mountain contains fossil remnants of massive prehistoric corals and large seashells.

The north face has impressive 1,000 m (3,300 ft) high cliffs, towering over the valley of Atxondo.

The south face descends more smoothly toward the pass of Urkiolamendi; more even, it is used for the more popular routes of ascent.

In a cave close to its summit, the legend tells us that Mari, the "Lady of Anboto", has her main dwelling.

It is not rare either to see her spend nights as a great ball of fire in the sky above Anboto or other places of the Basque Country where she possesses dwellings like the nearby Oiz or Aizkorri.