Object templates 17, 18 and 19 are two pieces at one place: a creature (graphic 94, 86 or 87) and under it graphic 11, its lower half, in the next record. The lower half does nothing of its own: it is put straight under the record before it -- the same U and V, 12 lower -- after that record's update has moved it, and is redrawn whenever the upper half has any step.

The footstep it asks for never sounds: LOWER_HALF_STEP plays only on an even graphic, and 11 is odd. The simulator sessions never ran that part of LOWER_HALF_STEP (see the coverage report).