These are barnacles, which are interestingly related to lobsters. See the image for comparision (from here):
They have a mobile larval stadium, but once they mature, they attach to a hard surface. They can be found on ships, surfaces in harbours, on whales and obviously on lobster shells. See here and here for some more details.
I think this is probably a checkered puffer Sphoeroides testudineus based on your location and picture, with the wave-reflection patterning on the dorsal surface and ventral speckling the most obvious features.
(image from https://biogeodb.stri.si.edu/caribbean/en/thefishes/species/4403 )
Could be a different Sphoeroides, but I looked through other species ...
@Alex's answer found a very close match with Pseudothemis jorina but as pointed out there that species is generally found in Southeast Asia, not Taiwan or Mainland China.
Pasting Pseudothemis jorina in the species search box in https://www.inaturalist.org/observations (found in this answer to Identify this large, beige or pine cone-colored squareish beetle ...
The closest match I can find is Pseudothemis jorina:
It's very similar to your pictures in regards of body shape and the light distinct band, although I'm not sure it would normally be found in Taiwan. It's more common further south like Thailand and Malaysia.
Looks like this species is Orthetrum triangulare commonly known as blue-tailed forest hawk.
It is an Asian fresh water dragon fly species.
As you mentioned that the dragonfly had a bluish hue, it became clear.
Since a similar type of this, called Orthetrum albistylum commonly known as black-tailed skimmer is found in Central and South Europe to China and ...
That looks very much like a brown color morph of the Box tree moth (Cydalima perspectalis), which has been seen in the UK since 2008. The size is about right (around 4.0-4.5 cm wingspan).
This species is an invasive pest outside of its native range (Asia).
By Nagy Sándor (NagySandor.EU) CC BY 3.0, Link
According to the Royal Horticultural Society this ...
According to the Israeli Scorpions Field Guide, deathstalkers can have also pale metasomal segment V, so a black one isn't a sure identification sign although it is very common among deathstalkers. The characteristic of the Israeli deathstalker are 5 ridges along its back. The species of deathstalker in the Negev (and Israel) is Leiurus hebraeus.
I haven't found an official reference, just a mention that the metasomal segment V can be pale in some adults.
Perhaps after molting the colour is different?
Also, dont know if it is Leiurus quinquestriatus, L. hebraeus, or L. abdullahbayrami
I see picture with the same pale coloration at sciencedirect.com/topics/agricultural-and-biological-sciences/…
They are common hollyhocks, they come in many colors. As a little kid from Chicago , I was impressed by flowers taller than me when visiting rural Wisconsin . Then the standard for hiding/decoration outhouses.
It is a Barn Funnel Weaver (Tegenaria domestica), In Europe it is known as the domestic house spider.
Here's some photos of this species to prove the similarities:
What caught my eye in particular that made it more clear that it was this species was the color patterns on the abdomen and cephalothorax, the size you mentioned, the shape of the feelers as well ...
For California trees, my go-to is A Californian's Guide to the Trees Among Us by Matt Ritter (Heyday, 2011). California trees can be challenging due to the extremely varied habitat and many introductions over the years.
Your trees appear to be younger specimens of Pinus pinea or the Italian Stone Pine, based on the description on page 14 in Ritter. No other ...
This is a misbelief and the possible answer is "The Krait" and its subspecies.
Here is a blog post by a scientist in the Tata institute of fundamental research. The blog contains data compiled from various sources for the "Special Interest Group-Snakes newsletter, I.I.T. Bombay".
As per the blog post
"In northwestern India, kraits ...