  Searches for dark matter with liquid xenon time projection chamber
experiments have traditionally focused on the region of the parameter space
that is characteristic of weakly interacting massive particles, ranging from a
few GeV/$c^2$ to a few TeV/$c^2$. Models of dark matter with a mass much
heavier than this are well motivated by early production mechanisms different
from the standard thermal freeze-out, but they have generally been less
explored experimentally. In this work, we present a re-analysis of the first
science run (SR1) of the LZ experiment, with an exposure of $0.9$
tonne$\times$year, to search for ultraheavy particle dark matter. The signal
topology consists of multiple energy deposits in the active region of the
detector forming a straight line, from which the velocity of the incoming
particle can be reconstructed on an event-by-event basis. Zero events with this
topology were observed after applying the data selection calibrated on a
simulated sample of signal-like events. New experimental constraints are
derived, which rule out previously unexplored regions of the dark matter
parameter space of spin-independent interactions beyond a mass of 10$^{17}$
GeV/$c^2$.
