Eiko & Koma’s dance is like some prehistoric discovery in an unlikely place. You know the object must have had great significance because it’s so perfectly preserved, and before you can fathom its meaning, you feel its mystic power. Eiko & Koma’s movement is essentially the same from one dance to another: earthbound, contracted, they press through space as if their eyes hadn’t evolved yet, drawn to each other like agents in some primal process of growth and decay. But theatrically engineered elements of time, terrain, weather, and light around them suggest they might be engaged in more sophisticated social and environmental situations.

In Snow, the older of two pieces they showed last weekend at Northeastern’s Blackman Theatre under the auspices of CRASHarts, Eiko appears out of a snowswept void. The only light besides the snowflakes whirling down seems to come from Eiko herself, a pale wraith who hovers on the brink of invisibility — waiting, listening, not moving except to make microscopic corrections when she tilts or twists off balance. After a long time, another figure, Koma, slowly emerges behind her. She isn’t afraid, she might even be expecting him. She recognizes his familiar presence without looking at him. They enact a slow, intimate duet of embracings and leavetakings, of desire that never surges to passion.

In kabuki theater, the ghosts of the dead return to their lovers or enemies — not always to haunt or reproach, but sometimes to comfort. Eiko and Koma are influenced by kabuki and by butoh, the great 20th-century Japanese theater-dance form. But though their work fuses these two genres, it’s much less elaborate and less violent than either one. Each piece concentrates on a single image that takes shape very gradually and accumulates resonance. Nothing much seems to change, but the possibilities multiply. Snow could be about ghosts, or memory, or the long life of a couple.

Offering, premiered in 2002 and adaptable for either indoor or outdoor performance, again started with enigmatic figures and left the audience to interpret their actions. The dancers came down the aisles of the theater, bent and halting, their faces chalky white, like two very old people who had to rest whenever they took a few steps. One — in the dim light I could just recognize it was Eiko — feebly pulled herself up onto the stage and sank onto a pile of dirt. She lay there, leaning tensely on her elbows, while Koma lurched to the stage.

He curled up beside her, as if they’d always slept together, but neither one looked comfortable. She didn’t respond to him, and her head fell back into the dirt. Maybe she was already dead, but he nuzzled her the way a dog tries to wake its master. He lifted her limp torso, then scratched some of the dirt together to pillow her head. Resigned perhaps, he scooped handfuls of dirt over her and smoothed it like a shroud, then climbed on top of her. As he was doing this, an uncanny change came over her. Without moving, she came back to life.

After a while, they rose together and made their way to a large, cube-shaped object with huge horns or branches sticking out from its sides. They reconnoitered the object — I thought it was an altar — and seemed to be trying to climb onto it. Stones and dirt got scraped off and made alarming sounds as they hit the floor. Eiko did get on top of the altar and rose with a look of triumph, shoving a handful of dirt into her mouth.

This seemed to be the first phase in an extraordinary ritual that I thought encompassed loss and replenishment. Koma had to serve in the role of destroyer, to prepare the woman who’d been his partner for sacrifice. He brought arrows and drove them into the dirt around her prone body, symbolically piercing her and planting them, like rice shoots. He somehow undid his red gauze sarong and draped it around her; she’d already lost whatever clothes she’d worn. He embraced her from behind, then reinforced the procreative act by stuffing dirt into her mouth. She fell back, and he crawled to the other side of the altar, dangling over the edge, spent or dead, as snow started to fall.

By the word Offering, Eiko and Koma seem to intend a two-sided gift to the gods, or to history. Maybe survival is only possible through giving up life. Maybe love demands death, and death nourishes the future. Sober thoughts in a grim time.