shipworm: wormlike marine bivalve that bores into wooden piers and ships by means of drill-like shells
entity: that which is perceived or known or inferred to have its own distinct existence (living or nonliving)
triiodothyronine: thyroid hormone similar to thyroxine but with one less iodine atom per molecule and produced in smaller quantity; exerts the same biological effects as thyroxine but is more potent and briefer