Rare sand dollar at Lazarus?

Yesterday, I was back at the reclaimed sandy lagoon at Lazarus Island which I visited one month ago.

The tide wasn't very low but I found many more common sea stars (Archaster typicus) on top of the only two found during the previous trip. It was exciting to see many of these sea stars colonizing this artificial beach.

I only had a quick walk around because the drizzle turned into a downpour. Nevertheless, there were several Creeper snails (Family Cerithiidae),Dubious nerite snail (Clithon oualaniensis), Sand collars of moon snails (Family Naticidae), Horn-eyed ghost crab (Ocypode ceratophthalmus), Spoon seagrass (Halophila ovalis), and also many Cake sand dollar (Arachnoides placenta).

What surprises me are several dead tests of sand dollars.


A closer look at these tests reveal that these does not belong to the Cake sand dollars based on its size and shape.

The underside reveals the the middle portion is hollow.

I suspect that this is the rare Laganum sand dollar (Laganum depressum) and the test matches the description of this Laganum sand dollar at the Wildfacts page.

"Body diameter 4-6cm. Somewhat pentagonal rather than circular. On the upperside it is thick at the edges and at the centre, and thinner elsewhere, creating a shallow circular depression around the centre."

This rare sand dollar is listed as 'Vulnerable' on the Red List of threatened animals of Singapore.

I look forward to check out this lagoon in the future during a lower spring tide to find them alive than the washed up tests of these rare sand dollars.