Evening star., 1937-05-22
STARS, MEN AND ATOMS
Notebook of Science Progress in Field,
Laboratory and Study.
BY THOMAS r. HENRY.

There are creatures which spend their
whole lives building their own tombs.
They constitute a group OF bivalve
mollusks which is related to the clans
and oysters. They are very ancient
animals. Their self-made sepulchres
may endure for a hundred million
years or more to puzzle students OF the
enigmatic pages of the rocks, but finally
proving valuable indices of the shifting
bounds of geologic time.
Some exceptionally interesting exam
pies Of these tombs, whose builders lived
on the sea bottom which now consti-
tutes coastal formations of New Jersey
and Maryland about 50000,000 years
ago, have just come into the Smith
sonian Institution collections. They
are described in recent report to the
National Academy of Sciences by Lloyd
w. Stephenson of the Geological Survey.
The tombS themselves are hollow,
pipelike tubes. four to six inches long,
found in sedimentary rock laid down
on the ancient sea bottoms. The pipes
taper off gradually from bottom to top
In the bottom may be found the empty
shell of the ancient tomb builder.
In its habit of growth" says Mr..
Stephenson, this bivalve began at
young stage to bore in the sand and
to construct a tube of calcium carbonate
around itself. AS it bored deeper and
grew larger. it gradually increased the
size of it's tube and eventually reached
a size such that it could not escape
backward out of it's self-constructed
prison.
All the time, Of course, the mollusk
maintained it's connection with the
water outside through a long syphon
reaching through the small end OF the
tube through which came the water
from which, like an oyster or clam, 1t
filtered it's sustenance.
Why did the creature thus spend It's
days boring further and further into
the dark? Moralists might find paral-
lei in human behavior. The only rea-
son that can be assigned is that OF
protection. Even with the armour OF
it's shell-which did not cover all its
body-and the concealment obtained by
burying itself in sand the creature was
more or less at the mercy of its enemies,
sea creatures who scooped in the bottom
for their sustenance.
1t sought security by secreting an
outer shell of calcium carbonate around
itself. AS it grew, its self-constructed
quarters became cramped. 1t must find
more space, and the only direction in
which it could go was downward. Con-
tinually, as it bored deeper and deeper,
it kept secreting the calcium carbonate.
How it bored is matter OF conJec-
ture. This particular creature, sup
posedly tunneled it's way only through
loose sand Some relatives, however,
even today bore their way into coral and
even solid rock. A relative is the ex-
tant shipworm, which causes incal-
culable damage by boring in wood.
Mr.. Stephenson assigns the ancient
creature to the group Of mollusks known
as pelecypods. Many relatives, it Is
explained, still are living and are rather
widely distributed in shallow sea waters.
Their ways Of life are so secretive. how
ever, that they are seldom observed and
little is known about their habits, their
boring mechanisms, etc.
The particular creatures described by
Mr.. Stephenson are assigned to a new
genus, the kummelia, and are of par
ticular interest, since they show that
certain coastal formations belong to the
eocene rather than the cretacious geo.
logical period. They were boring their
strange sepulchres in the days when
the age Of birds and mammals was
daVptnR,