Leatherbacks rhymes with:
paperbacks, quarterbacks, razorback's, razorbacks, buybacks, comebacks, cutbacks, drawbacks, flashbacks, fullbacks, givebacks, greenback's, greenbacks, halfbacks, kickbacks, leasebacks, paperbacks, paybacks, pricklebacks, pullbacks, quarterbacks, razorback's, razorbacks, rollbacks, setbacks
Leatherbacks sounds like:
lauderback, lauderbaugh, lauterbach, leatherback, louderback