Umbraculum f rom Florida

July 16, 2004
From: Robert Shearer

Large Umbraculum sighting. Sorry, no picture. . .

LOCATION: off Boca Raton, Florida
LATITUDE: 26 19.281, LONGITUDE: 80 03.538
DATE: 9 May 2004, TIME: 10:30am

Found loose on sand in coral trail between the wreck of Sea Emperor and the United Caribbean.

It looked like a 9-10inch [25cm] diameter orange sphere, seemed uniform all around at first -- sort of like cauliflower head with similar surface shape (texture like the surface of a brain). It had a depression on the bottom without the warty surface. It had some white stringy, wispy material on the surface.

When I picked it up, it was not attached at all to the sand. It was soft and pliable (like soft foam they make some mattresses from) and the surface reshaped readily. On the top center was a flat oval-shaped 2x3"disk that seemed hard/calciferous. There was almost no growth on it and showed slight concenteric circles like growth lines on an operculum. When I pushed the body away from the disk slightly, you could see that it was attached by a 3/4" high, slightly converging structure, like a fat stalk. This was made up with a repeating pattern that looked like pieces cut from the middle part of feathers -- shaft with branching lines (gills). When you let the body go, the disk recessed until this attachment was again not visible, the disk flush with the surface of the body.

It didn't seem to have any internal shell or rigid structure that I could feel. Meanwhile, the depression on the bottom had opened out on my gloved hand and the body edging it had molded to the shape of my hand. I could pull my hand away fairly easily. The surface of this depression had a flatter, denser surface than the body with very small lobes compared to the body. I couldn't see anything of a "mouth" (as an anemone migh have). I fanned away some of the white material, but it seemed to reappear. The color seemed more pinkish as I brought it to the surface -- still uniform all over accept the disk that was grey-white. I carried it to the surface and had the DM put it in a bucket while I went back to finish the dive.

Unfortunately, no one took a picture of it and I felt compelled to let it go before leaving, so I don't have a specimen. I should have known better, but I thought I might be some sort of rare local critter, so didn't want to remove it.

ID confirmed by similar structured critters on the Forum [messages #2542 #7832]. However, this one was much larger. I do not know if this is really an exotic or rare species. I see that others have been photographed in the area.

Robert Shearer

Shearer, R., 2004 (Jul 16) Umbraculum f rom Florida. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Robert,
It certainly sounds like Umbraculum. We have no idea just how common these animals are. Their shape and appearance, and the growths that often grow on their external shell help to camouflage them from all but the most diligent searchers. There are also reports of them burying in shell sand, at least to shell level, which also means it will be difficult to get an accurate idea of their abundance.
Best wishes
Bill Rudman

Rudman, W.B., 2004 (Jul 16). Comment on Umbraculum f rom Florida by Robert Shearer. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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