baby horseshoe crabs

Today we walked out half way around Morris Island

and found an area with many baby horseshoe crabs

unburying themselves and crawling around as the tide came in.

We might have missed them if we hadn't seen an exhibit Wednesday at the Cape Cod Museum of Natural History of one-year-old horseshoe crabs, which were tiny. The volunteer said horseshoe crabs take 10 years to reach sexual maturity. So how old was one like this?