Last week I gave you this specimen from the Dead Zoo to have a go at identifying:

I don’t often do molluscan mystery objects, but the unexpected spike on this shell really caught my eye.

It is very distinctive, so I wasn’t overly surprised by the correct answers from several people – Tony Irwin even managed a nice cryptic clue playing on the scientific name for this species:

“Could be a young wizard’s spell to make something not quite round, perhaps using a wand made from a bit of blackthorn?”

This is of course alluding to Elliptio spinosa (I. Lea, 1836), known more commonly as the Altamaha or Georgia Spinymussel.

These freshwater mussels are endemic to America and are limited to large, fast-flowing rivers in Georgia. They are currently endangered, partly due to changes in their river habitat (such as increasing ammonia pollution in water) and partly due to a decline in the species of fish that they rely on as hosts for their parasitic larval stage.

I’m not certain what the spines are for, but since these mussels live in the sediment of fast-flowing rivers, they may simply act as anchors to help prevent them from being dislodged.

A bit of a short answer this week, but I’m typing one-handed due to an injury and I need some rest. I will endeavour to have another mystery object for you next week though!