Interesting Abalone Pearl

[GemGeek]

For your viewing pleasure. A gentleman named Travis found this pearl in an abalone in Northern California. It had a worm-like critter living inside the hole, which he was planning on cleaning out. It's about 1.5 inches across.

 

[Caitlin]

That is so interesting! and It is a pretty pearl for being so large...

 

[Rachfrog]

That is the weirdest, yet coolest thing I've ever seen...Do you think the worm caused the pearl formation? Which came first, the worm or the pearl?

 

[GemGeek]

Here is Lagoon Island Dave's response: This type of pearl is normally formed by a perforation in the mantle skirt (as opposed to the typical horn shapes from hepatopancreatis) Very often tiny parasites are encased, but in this case the animal's growth rate exceeded the abalone's. The oval shape and imprint suggests a chiton. The original hole was likely drilled by a gastropod and when it became dislodged the critter crawled inside.

 

[GemGeek]

I agree about the weirdest coolest. I got very excited when I saw it. I've never seen one like it.

 

[Lagoon Island Pearls]

Here is Lagoon Island Dave's response: This type of pearl is normally formed by a perforation in the mantle skirt (as opposed to the typical horn shapes from hepatopancreatis) Very often tiny parasites are encased, but in this case the animal's growth rate exceeded the abalone's. The oval shape and imprint suggests a chiton. The original hole was likely drilled by a gastropod and when it became dislodged the critter crawled inside.

A worm is possible, but most worms leave spiral impressions. This pearl has an oval margin and flat surface within, which is smooth. The reluctant passenger had an oval shaped mantle that occupied the adjacent space. (By the way, many chitons and limpets have a single scale worm in the mantle cavity, so this could even be a three way symbiotic) There also appears the be a small grazing area at one end, where the radula had enough movement to gather bits food. A limpet might have otherwise blocked the point of entry, but a chiton has an articulated, flexible shell which likely allowed new seawater to circulate in the cavity to let algae form, which in turn fed the chiton. As the critter grew, it put inward pressure on the host's mantle, causing thickening to the structure in the extrapallial space.

Things living in things happens often, but to this degree is really interesting. It looks like a wax seal used on old letters and has nice from with clean edges and very little brown patching from conchiolin. It's intriguing what the owner will do with it. I can see a bezel, cabochon or cameo in that impression.