M60 tanks undergo a thorough cleaning before use as reefs
The Artificial Reef Program used four types of obsolete Army armored vehicles as artificial reef materials off the New Jersey coast. These were cleaned at local military bases, loaded onto barges for transport, and pushed off at their final destination. Once the Army had disposed of its excess inventory, the program ceased, around 1999. The Artificial Reef Program has sunk almost 400 tanks altogether, far too many to list them here in this website.
"Higher animals" is a catch-all term for vertebrates other than fish. This is rather self-congratulatory, since the so-called "lower animals" - fishes and invertebrates - are actually the dominant species on the planet, both in numbers and diversity! The four classes of higher animals are:
Amphibians - class Amphibia
Reptiles - class Reptilia
Birds - class Aves
Mammals - class Mammalia
Of these, amphibians are absent from marine environments ( with one or two exceptions. )