Bring the hammer.

Prepare yourself for the hammer.

Mc Hammer Dance Gif By Agent M Loves Gif - Find & Share on GIPHY

No not that hammer. This one.

Naturalis Biodiversity Center - ZMA.MOLL.1264 - Malleus malleus (Linnaeus, 1758) - Malleidae - Mollusc shell

The Malleidae, or the hammer oysters, is a suite of around 30 species, primarily in the genus Malleus, all with a hammer or T shape to the shell.  I mean look at this shell.

I like to think in the evolution process a conversation like this occurred.

Representative of all other clams, oysters, and scallops: So I thought we all a voted on this…and umm…agreed that our shells would be sort of roundish.

Malleus: You know I got to drop the Hammer!

Representative: Well you know is just that we kind of agreed on this. We really all need to be roundish.

Malleus: You can’t stop the Hammer!

Representative: What about a nice kind of tear drop shape?

Malleus: Can you feel the Hammer!

Representative: We could give you some cool wings or tabs?

Malleus: Hammer!

Representative: What about you some flashy spikes?


Representative: Now your just being unreasonable.


Representative: Why are you shouting?


So why the hammer shell? Does Malleus crawl around and drop the hammer pain on unexpecting prey or predators? Do the shelled wings allow allow for some other bad-assery?

The function of the hammer shell is perhaps a little more vanilla. Hammer oysters typically inhabit the course sands around coral reefs. Those wings, buried in the sand, serve as anchor, allowing the hammer oyster to stay in place as currents threaten to cary the oyster away.

Hammer oysters often take a battering from currents and debris propelled through the water. This often damages the shell. In the words of the famous naturalist, Charles Maurice Yonge, an expert on bivalves, “It is rare to find a large shell which does not exhibit extensive areas of repair. An example (from Rabaul) is shown in Figure 5A, the animal has withdrawn from a broken extent of distal shell and formed a new one at a somewhat different angle….Such changes may be in any plane and many adult shells are of grotesquely distorted appearance.”

Dr. M (1801 Posts)

Craig McClain is the Executive Director of the Lousiana University Marine Consortium. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Additionally, Craig is obsessed with the size of things. Sometimes this translated into actually scientific research. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (, a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.